OF 


EDUCASIOS 


G.  S   WHITFORD. 


THE 


SCIENTIFIC  CLASS-BOOK; 

OR, 

A    FAMILIAR    INTRODUCTION    TO    THE    PRINCIPLES 

OF 

PHYSICAL  SCIENCE, 

FOR     THE     USE     OF     SCHOOLS    AND     ACADEMIES. 
ON    THE    BASIS    OF    MR.    J.    M.    MOFFATT. 

PART    II. 

COMPRISING 


CHEMISTRY, 
METALLURGY, 
MINERALOGY, 
CRYSTALLOGRAPHY, 


GEOLOGY, 
ORYCTOLOGY, 

AND 
METEOROLOGY. 


WITH    ADDITION'S,    EMENDATIONS,   NOTES,    REFERENCES,    QUESTIONS   FOR 

EXAMINATION,  LISTS    OF   WORKS   RELATING  TO   THE   SEVERAL 

SUBJECTS,    SOME   ADDITIONAL    ILLUSTRATIONS, 

AND   A   COPIOUS   INDEX. 

BY  WALTER  R.  JOHNSON,  A.M. 

Professor  of  Mechanics  and  Natural  Philosophy  in  the  Franklin  Institute  of  the  State  of  Pennsylvania, 

Member  of  the  Academy  of  Natural  Sciences  of  Philadelphia,  and  one  of  the 

Vice  Presidents  of  the  American  Institute  of  Instruction. 


PHILADELPHIA : 

PUBLISHED  BY  KEY  AND  BIDDLE. 
1836. 


ENTERED  according  to  Act  of  Congress,  in  the  year  1836,  by 

KEY  &  DIDDLE, 

in  the  Clerk's  Office  of  the  District  Court  of  the  Eastern  District  of 
Pennsylvania. 


EDUCATION  LIBS. 


STEREOTYPED    BY    L.JOHNSON, 
PHILADELPHIA. 


. 

CONTENTS. 


CHEMISTRY. 

Definition,  9 — Objects  of  the  Science,  ib. — Attraction  of  Aggregation 
and  Attraction  of  Composition,  9 — Modes  of  Aggregation,  10 — Effect  of 
Chemical  Combination,  12 — Simple  and  Compound  Substances,  14 — Table 
of  Simple  Substances,  16 — Oxygen,  18 — Nitrogen,  18 — Hydrogen,  19 — 
Chlorine,  20 — Carbon,  21 — Silicon,  ib. — Boron,  Sulphur,  Phosphorous,  22 
— Iodine,  Bromine,  Fluorine,  23— Selenium,  24 — Metals,  ib. — Chemical 
Affinity,  26— Laws  of  Chemical  Affinity,  27— Elective  Attraction,  28— 
Divisibility  of  Matter,  29 — Combustion,  34— Influence  of  Heat  on  Solution, 
38 — Electricity,  40 — Metallic  Crystallizations,  46 — Animal  Electricity, 
48 — Spontaneous  Combustion  of  the  Human  Body,  49 — Theory  of  Definite 
Proportions,  52 — Atomic  Weights  of  Bodies,  53 — Dr.  Wollaston's  Scale  of 
Equivalents,  57 — Simple  and  Compound  Elective  Attraction,  62 — Primary 
and  Secondary  Chemical  Compounds,  66 — Observations  on  Simple  Bodies 
and  their  Primary  Compounds,  69 — Table  of  Binary  Compounds  of  Non- 
metallic  Elements,  70 — Oxygen,  Oxides,  and  Acids,  73— Chlorine  and 
Chlorides,  78— Iodine,  lodic  Acid,  81— Bromine,  Bromic  Acid,  83,84— 
Fluorine,  85— Hydrogen,  87— Water,  88— Muriatic  Acid,  92— Nitrogen,  95 
—Oxides  of  Nitrogen,  96— Acids,  98— Chloride  of  Nitrogen,  99— Ammonia, 
100 — Carbon,  Diamond,  101 — Carbonic  Oxide,  103 — Acids,  ib. — Compounds 
of  Hydrogen  and  Carbon,  109— Cyanogen,  112— Boron,  Boracic  Acid,  113, 
114— Silicon,  116— Silica,  117— Phosphorus,  119— Oxides  and  Acids,  121— 
Combinations  with  Hydrogen,  124 — Sulphur,  126 — Acids, 127 — Sulphurets, 
131— Selenium,  132— Acids,  133— Metallic  Elements,  134— Classification 
of  Metals,  136— Tables  of  Binary  Combinations  of  Metallic  and  Non- 
metallic  Elements,  137,  138,  139 — Arsenic,  139 — Antimony,  Columbium, 
Titanium,  140— Chrome,  Molybdena,  Tellurium,  Tungsten,  .141 — Vana- 
dium, Uranium,  Manganese,  142 — Cobalt,  Tin,  143 — Potassium,  145 — So- 
dium, 147— Lithium,  148 — Baryum,  149— Calcium,  Strontium,  150 — Mag- 
nesium, 151 — Aluminum,  Zirconium,  152 — Glucinum,  Yttrium,  Thorinum, 
153— Iron,  156— Nickel,  Zinc,  Cadmium,  Cerium,  157— Lead,  Copper,  Bis- 
muth, 158 — Mercury,  Silver,  Gold,  159— Platina,  Palladium,  Rhodium, 
Iridium,  Osmium,  and  Analysis,  160 — Analysis  of  Earths  and  Stones,  161 
—Vegetable  Kingdom,  164 — Analysis  of  Vegetables,  167 — Animal  King- 
dom, 168— Soils,  170— Analysis  of  Soils,  172— Mineral  Waters,  176— 
Testing  of  Mineral  Waters,  177— Works  on  Chemistry,  185. 

METALLURGY. 

Definition,  186 — Mineral  Deposits  and  Mines,  187 — Mineral  Veins, 
188 — Metallic  Ores  and  their  Localities,  193-196 — Art  of  Mining,  196- 
209— Docimacy,  209— Assaying  by  the  Dry  Method,  210 — Assaying  by  the 
Moist  Method,  213— Reduction  of  Metallic  Ores,  215— Gold,  216— Silver, 
218— Platina,  219— Mercury,  220— Iron,  221— Tin.  225— Copper,  226— 
Lead,  228— Zinc,  229— Alloys,  231— Works  on  Metallurgy,  235. 

MINERALOGY. 

Preliminary  Observations,  236 — Classification  of  Minerals,  237 — Proper- 
ties of  Minerals,  238 — Constituents  of  Mineral  Substances,  243— Arrange- 
ment, 244 — Table  of  Mineral  Classes,  246 — Elettro-positive  Native  Metals, 
249 — Electro-negative  Substances  and  their  Non-oxidized  Combinations, 


JVJ5l770fiO 


CONTENTS. 

249 — Tellurium  and  Tellurets,  ib. — Arsenic  and  Arseniurets,  250 — Carbon 
and  Carburets,  ib. — Selenium  and  Seleniurets,  251 — Sulphur  and  Sulphu- 
rets,  252— Oxides  of  Electro-positive  Metals,  256 — Oxides  and  Oxacids  of 
Electro-negative  Substances,  258— Alumina  and  Aluminates,  ib.— Silica 
and  Silicates,  258,  261— oxide  of  Titanium  and  Titanates,  267— Columbia 
Acid  and  Columbates,  268— Antimonic  Acid  and  Antimoniates,  ib. — Tung- 
states,  ib.— Molybdic  Acid  and  Molybdates,  269— Chromic  Acid  and 
Chromates,  ib. — Vanadic  Acid  and  Vanadiates,  270— Boracic  Acid  and  Bo- 
rates,  ib. — Carbonates,  271 — Arsenious  Acid  and  Arseniates,  275 — Phos- 
phates, 276 — Nitrates,  277 — Sulphates,  ib.— Fluorides,  279— Chlorides,  280 
— Organo-chemical  Substances,  281 — Works  on  Mineralogy,  282. 

CRYSTALLOGRAPHY. 

Figures  of  Crystals,  284 — Isomorphism,  285— Haiiy's  Theory  of  Crystal- 
lization, 288 — Primitive  Forms,  290 — Law  of  Decrements,  293— Goniome- 
try,  295 — Crystallometrical  System  of  Mohs,  296— Works  on  Crystallo- 
graphy, 297. 

GEOLOGY. 

Introductory  Remarks,  298— Cosmogonical  Speculations,  299— Theories 
of  Werner  and  Hutton,  300— Researches  of  Cuvier,  302— Progress  of  Geo- 
logical Science,  303 — Figure  of  the  Earth,  304 — Density,  305— Specula- 
tions on  the  Central  Structure  of  the  Earth,  306— Subterranean  Tempera- 
ture, 308— Thermal  Springs,  312— Temperature  of  the  Atmosphere,  315— 
State  of  the  Earth's  Surface,  317— State  of  the  Crust  of  the  Earth,  318— 
Modifying  Action  of  Existing  Causes,  319— Influence  of  the  Atmosphere, 
324 — Deluges  of  Sand,  333 — Hurricanes,  334 — Influence  of  Water,  336 — 
Destructive  Effects,  ib.— Land  -floods,  339— Alluvial  Islands,  340— Deba- 
cles, 342 — Landslips,  345 — Bursting  of  Bogs  and  Mosses,  346 — Action  of 
Frozen  Water,  348— Effect  of  Waves  and  Breakers,  349— Deposits  from 
Hot  Springs,  351 — Submarine  Formations,  353 — Earthquakes,  357 — Vol- 
canos,  361 — Causes  of  these  Phenomena,  367 — Remarks  on  the  Analogy 
between  Ancient  and  Modern  Disturbances  of  the  Earth's  Surface,  368— 
Formation  of  Valleys,  373 — Erratic  Blocks,  375 — Elevation  of  Mountains, 
377 — Mineral  Structure  of  Rocks,  380 — Mechanical  Structure,  385 — Clas- 
sification and  Arrangement  of  Rocks,  391 — Table  of  Groups,  Formations, 
and  Rocks,  393— Works  on  Geology,  397. 

ORYCTOLOGY. 

Modes  of  Fossilization,  400 — Geological  Arrangement  of  Minerals  and 
Fossils,  405 — Primordial  Rocks  and  their  Minerals,  407 — Fossil  Remains 
in  Submedial  Rocks,  409 — in  Medial  Rocks,  412 — in  Supermedial  Rocks, 
419 — in  Tertiary  Rocks,  426 — in  Alluvial  Deposits  and  Bone  Caverns, 
428— Oryctology  of  the  United  States,  433— Works  on  Oryctology,  435. 

METEOROLOGY. 

Preliminary  Remarks,  436 — General  Observations  on  the  Atmosphere, 
437 — Variations  of  Atmospheric  Pressure,  439 — Winds,  440 — Causes  of 
Winds,  441— Periodical,  Variable,  and  Local  Winds,  443— Velocity  of 
Winds,  445— Hygrometry,  446— Saussure's  Hygrometer,  448—  Darnell's 
and  other  Dew-point  Hygrometers,  449,  450 — Clouds,  450 — Formation,  451 
Constitution,  452 — Modifications,  453 — Cirrus,  454, — Cumulus,  455. — Stra- 
tus, ib. — Cirrocumulus,  456 — Cirrostratus,  ib.— Cumulostratus,  457 — Nim- 
bus, ib.— Rain,  ib.— Snow,  458— Hail,  459— Dew,  460— Hoar-frost,  461— 
Ground-ice,  462— Optical  and  Electrical  Phenomena,  463— Aerolites,  ib. 
— Works  on  Meteorology  464. 


PREFACE. 


THE  same  reasons  which  impelled  us  to  undertake 
the  adaptation  of  the  first  part  of  the  "  Scientific  Class 
Book"  to  the  use  of  schools  and  academies  in  the  United 
States,  has  equally,  or  even  more  forcibly,  urged  the 
importance  of  performing  the  like  task  in  regard  to 
the  present  work.  In  several  of  the  departments  in- 
cluded in  this  volume,  we  have  hitherto  been  so  far 
from  possessing  a  good  treatise  adapted  to  schools,  that 
we  have,  in  fact,  had  no  work  in  all  respects  eligible  as 
a  text  book,  even  for  the  highest  institutions. 

This  deficiency  cannot  be  said  to  arise  from  a  want 
of  interest  to  create  a  demand  for  information  in  regard 
to  the  sciences  here  sketched.  The  remarkable  ra- 
pidity with  which  the  arts,  dependent  for  their  success 
on  these  divisions  of  knowledge,  have  recently  ad- 
vanced, evinces  that  high  national  interests  are  con- 
cerned in  the  diffusion  of  correct  notions  respecting 
their  phenomena  and  laws. 

The  treatise  on  Chemistry  will  be  found  to  contain  a 
general  discussion  of  the  objects  of  the  science,  a  concise 
view  of  the  various  simple  substances  of  which  it  treats, 
and  the  chemical  laws  of  combination,  together  with  a 
brief  account  of  the  non-metallic  and  the  metallic  ele- 
ments, and  their  respective  compounds.  We  have 
added  a  considerable  number  of  illustrations;  and  ar- 
ranged and  condensed,  from  the  excellent  Chemical  Dic- 
tionary of  Dr.  Ure,  the  articles  on  analysis  of  stones — 
on  the  vegetable  creation,  its  chemical  constituents,  and 
modes  of  analysis — on  the  animal  kingdom  and  its  che- 
mical relations — on  the  nature  of  soils,  with  the  methods 
of  testing  and  improving  their  character,  as  detailed  by 
Davy  and  others,  and  on  the  constitutions  and  tests  of 

A2  5 


6  PREFACE. 

mineral  waters.  Without  these  additions  the  treatise 
on  Chemistry  would  haye  lacked  much  of  its  value  as  a 
practical  elementary  guide.  With  these,  the  usefulness 
of  the  science  is  at  once  made  manifest,  and  the  methods 
of  operating,  presented  in  the  subsequent  parts,  in  which 
the  treatment  of  metallic  ores  and  other  minerals  is 
described,  become  intelligible  and  of  easy  application. 
The  nomenclature  employed  in  this  department,  is  in 
accordance  with  the  usage  of  the  most  approved  modern 
writers. 

The  tract  on  Metallurgy  will,  it  is  confidently  be- 
lieved, be  found  to  embrace  a  highly  useful  series  of 
elementary  facts  and  instructions,  upon  a  department  of 
science  and  art  rapidly  rising  in  the  estimation  of  the 
community,  and  upon  which  hitherto  very  little  general 
information  has  been  diffused.  The  subdivisions  of 
this  treatise,  relating  to  mineral  veins  and  mines — the 
art  of  mining,  and  that  of  assaying  by  mechanical 
means,  and  by  the  dry  and  humid  methods  respect- 
ively— the  metallurgic  processes  for  reducing  ores, 
with  the  methods  of  forming  alloys,  and  the  uses  to 
which  the  latter  are  severally  applied,  form  so  many 
highly  curious  and  interesting  topics  of  discussion, 
adapted  alike  to  stimulate  and  to  reward  inquiry. 

Among  the  branches  of  knowledge  which  now  engage 
the  intense  interest  of  the  scientific  world,  one  of  the  most 
attractive  is  that  which  relates  to  the  present  state  of  the 
earth's  surface,  and  to  the  crust  immediately  beneath  it. 
This  science  involves  the  necessity  of  understanding 
the  phenomena  and  principles  of  chemistry,  not  less 
than  those  of  mineralogy  and  the  laws  of  crystalliza- 
tion; and  it  leads  directly  to  the  development  of  those 
remarkable  truths  respecting  the  former  condition  and 
inhabitants  of  our  planet,  which  the  study  of  fossil 
geology  could  alone  impart.  The  freshness  of  these 
subjects  to  the  minds  of  American  students,  the  facility 
of  illustrating  them  in  all  their  details  by  the  observa- 
tion of  numerous  facts,  and  the  influence  of  those  dis- 
tinguished names  among  ourselves,  who  have  become 
connected  with  the  cultivation  of  these  several  sciences, 


PREFACE.  7 

and  to  whose  works  we  have  made  frequent  reference, 
will,  it  is  believed,  insure  to  these  treatises  the  attention 
which  their  subjects  must  ever  strongly  invite. 

However  remote  may  seem,  upon  a  limited  view,  the 
connection  between  the  study  of  such  subjects  as  that 
of  organic  remains,  and  the  direct  usefulness  of  its 
results,  yet  when  it  is  recollected  that  the  very  nature 
of  rocks,  the  value  of  minerals  which  may  be  expected 
to  accompany  them,  and  the  soils  they  may  aid  in  pro- 
ducing, are  all  indicated  by  the  kinds  of  organic  remains 
found  in  such  rocks,  it  will  be  apparent  that  most  useful 
knowledge  may  be  derived  from  this  study. 

In  works  of  science  the  style  is  a  matter  entirely 
secondary  in  its  relation  to  the  truths  of  nature  deve- 
loped. Studied  graces,  and  especially  ambitious  orna- 
ments of  mere  rhetoric,  would,  by  every  votary  of 
science,  be  felt  to  be  misplaced.  Neatness  and  perspi- 
cuity are  the  chief  characteristics  which  such  a  treatise 
demands;  and  these,  it  is  conceived,  have  been  ade- 
quately preserved,  maintaining  constantly  a  due  regard 
to  the  great  purpose  of  rendering  the  work  intelligible 
to  the  young,  without  offending  the  taste  of  the  more 
mature. 

In  preparing  the  questions  for  exercising  the  learner, 
the  same  view  has  been  maintained  which  guided  our 
labours  in  the  first  part  of  this  work.  We  are  far  from  con- 
sidering questions  unimportant,  whether  we  regard  them 
in  reference  to  classes  in  schools,  to  family  circles,  or  to 
private  students.  The  chief  inquiry,  in  relation  to  their 
usefulness,  seems  to  be,  whether  they  are  such  as  a  well 
qualified  teacher,  familiar  with  his  subject,  would  propose 
to  his  scholars.  We  leave  competent  persons  in  the 
profession  to  answer  the  inquiry,  with  regard  to  this 
division  of  our  labour;  merely  premising,  that  though 
a  vast  majority  of  teachers  probably  prefer  works  fur- 
nished with  this  subsidiary  to  their  instructions,  yet 
that  such  as  may  deem  their  own  questions  more 
appropriate,  or  more  intelligible  to  their  pupils,  than 
those  of  the  editor,  will  not  lie  under  any  necessity  of 
resorting  to  these;  and  it  is  certainly  anticipated  that 


8  PREFACE. 

none  will  content  themselves  with  the  exclusive  use  of 
the  latter.  Very  many  of  the  questions  are  designed 
merely  to  furnish  topics  arising  out  of  important  truths  or 
suggestions  contained  in  the  text,  on  which  the  familiar 
dissertations  of  the  teacher  may  be  founded;  and  if  he 
avail  himself  of  the  works  named  at  the  end  of  each 
treatise,  his  oral  explanations  will  possess  a  freshness  and 
interest  more  captivating  to  the  scholar  than  the  pages 
of  any  volume,  however  learned  or  well  written. 

The  distinguished  favour  with  which  teachers  have 
received  the  first  part  of  the  "  Scientific  Class  Book," 
has  stimulated  us  to  endeavour,  and  encouraged  us  to 
hope,  that  the  present  volume  may  not  be  found  less 
worthy  than  its  predecessor,  of  their  regard  and  accept- 
ance. 


CHEMISTRY. 

1.  CHEMISTRY  is  the  art  whereby  compound  bodies  are  changed 
into  simple  ones,  or  simple  ones  into  compounds.     The  former  of 
these  processes  is  called  Analysis  or  Decomposition,  and  the  lat- 
ter Synthesis  or  Composition.     As  a  science,  it  is  the  province 
of  Chemistry  to  determine  the  chemical  relation  of  simple  bodies, 
and  the  structure  and  chemical  relations   of  compounds.     Few 
of  the   operations  of  Chemistry,  which  are   employed  for  the 
attainment  of  these  objects,  are  either  purely  analytic  or   syn- 
thetic ;  a  combination  of  these  methods  generally  taking  place  in 
the  processes  of  the  chemist. 

2.  Different  kinds  of  matter  which  are  the  objects  of  Chemistry, 
possess  certain  active  properties,  such   as   gravity  or   weight, 
cohesion,  elasticity,  expansibility,  magnetic  attraction,  &c.     All 
these  properties  are  but  so  many  different  modifications  of  attrac- 
tion and  repulsion.     Action,  either  attractive  or  repulsive,  takes 
place  between  bodies  situated    at  various  distances   from   each 
other.     Thus  the  attraction  of  gravitation  operates  at  indefinite 
and  immense  distances ;  while  the  attraction  of  cohesion  affects 
the  particles   of  bodies  only  when  placed  in  apparent   contact. 
Repulsive  action  also  takes  place  at  different  distances.  Thus  tha 
repulsion  between  bodies  which  have  been  subjected  to  the  in- 
fluence of  electricity  or  magnetism  is  sufficiently  obvious  to  the 
sight ;  and  that  electric  or  magnetic  substances  which  repel  each 
other  do  not  touch,  may  easily  be   perceived.     The   expansive 
power  of  heat,  on  the  other  hand,  probably  affects  particles  of 
matter  nearly  in  contact  with  each  other. 

3.  The  various  phenomena  which  constitute  the  objects  of  Che- 
mistry, depend  on  the  operation  of  those  modifications  of  attrac- 
tive and  repulsive  force,  which  act  on  particles  of  bodies  placed  at 
insensible  distances  from  each  other,  and  are  so  minute  as  not  to 
he  cognizable  by  our  senses,  even  when  asssisted  by  the  most 
powerful  magnifying  glasses. 

4.  There  are  two  species  of  attraction  which  affect  particles  of 
matter  when  in  apparent  contact :  1.  The  Attraction  of  Aggrega- 
tion, or  Cohesion ;    2.  The  Attraction  of  Composition.     These 

What  is  the  office  of  chemistry,  considered  as  an  art  ? 

How  extensive  is  its  province  as  a  science  ? 

By  what  two  methods  are  its  purposes  effected  ? 

What  are  some  of  the  active  properties  of  matter  by  which  its  chemical 
changes  are  produced  ? 

What  is  the  true  nature  of  these  properties  ? 

What  is  the  difference  between  gravitation  and  cohesive  attraction? 

Under  what  different  circumstances  is  the  repulsive  action  of  bodies 
exercised  ? 

On  which  modification  of  attractive  and  repulsive  forces  do  chemical 
changes  depend  ? 

How  many  kinds  of  contiguous  attraction  exist  in  matter  ? 

9 


10  CHEMISTRY. 

powers  both  give  way  to  the  repulsive  action  of  heat  r'but  the  for- 
mer may  also  be  overcome  by  mechanical  force,  which  has  no  ef- 
fect on  the  latter. 

5.  The  Attraction  of  Aggregation  operates  differently  on  different 
bodies,  so  as  to  produce  the  various  degrees  of  cohesive  force  or 
consistence  observable  among  them.     The  forms  under  which  bo- 
dies appear  are  reducible  to  three  classes,  viz. :  Solids,  Liquids, 
and  Gases  or  Airs.     These  modifications  of  matter  are  influenced 
by  the  operation  of  mechanical  pressure,  and  the  expansive  force  ot 
heat,  which   seem   to  act  as  antagonist  powers  to   each   other. 
Some  kinds  of  matter  are  capable  of  existing  either  in  a  solid,  li- 
quid, or  gaseous  state,  under  different  degrees  of  atmospherical 
pressure  and  temperature.  Thus  water,  by  the  abstraction  of  heat, 
becomes  changed  to  ice  ;  by  the  addition  of  heat,  it  is,  on  the  other 
hand,  changed  to  vapour ;  and  that  change  is  facilitated  or  impeded 
by  lessening  or  increasing  the  atmospherical  pressure.     Mercury 
and  several  other  substances  exhibit  analogous  phenomena. 

6.  Many  bodies,  however,  commonly  exist  under  only  one  or  two 
forms  of  aggregation.     Common  air  and   other  bodies,   distin- 
guished from  vapours  by  the  designation  of  permanent  gases,  were 
formerly  supposed  to  retain  the  gaseous  forms  under  all  circum- 
stances ;  but,  from  the  experiments  of  Dr.  Faraday  and  Mr.  Per- 
kins, it  appears  that  atmospheric  air,  carburetted  hydrogen,  sul- 
phuretted hydrogen,  sulphurous  acid,  carbonic  acid,  protoxide  of 
chlorine,  nitrous  oxide,  cyanogen,  ammonia,  muriatic  acid,  and 
chlorine,  all  which,  under  common  temperature  and  pressures,  are 
permanent  gases,  may  be  condensed  to  the  liquid   state  by  the 
ioint  operation  of  intense  cold  and  powerful  compression.     How- 
ever, oxygen,  hydrogen,  and  some  other  gases  have  hitherto  re- 
sisted all  attempts  to  reduce  them  to  the  liquid  state.*     Several 
dense  solids,  as  lead  and  glass,  are  readily  melted  by  heat ;  but 
there  are  others,  as  wood,  which,  though  speedily  decomposed, 
when  heated  with  access  of  air,  cannot  be  liquefied.     The  facts 
already  stated,  and  others  which  might  be  adduced,  still  lead  to 
the  conclusion,  that  the  solid,  liquid,  and  gaseous  states  of  bodies 
depend  chiefly  on  their  respective  relations  to  temperature  and 
pressure  ;  and  therefore  the  distinctions  founded  on  those  states 
or  forms  of  matter  do  not  furnish  sufficient  grounds  for  general  ar- 
rangements of  bodies  in  separate  classes. 

Which  of  these  is  overcome  by  mechanical  means  ? 

By  what  causes  are  the  three  forms  of  matter  chiefly  influenced  ? 

Give  some  examples  of  variable  forms  in  matter. 

What  changes  of  form  may  be  mentioned  as  solely  due  to  the  effect  of 
caloric  ? 

In  what  instances  does  the  chemical  change  of  solids  take  place  without 
liquefaction  ? 

To  what  causes  are  we  hence  led  to  refer  the  several  changes  in  the 
forms  of  matter  ? 

*  See  Scientific  Class  Book,  pt  i.  p.  180. 


FORMS  OF  BODIES.  11 

'',.  Some  writers  have  treated  of  the  chemical  properties  of  gases 
or  airs  as  an  independent  branch  of  science,  under  the  appellation 
of  Aerology;  but  the  operation  of  bodies  under  their  different 
forms  are  so  intimately  blended,  and  the  condensation  of  gases  is 
so  commonly  the  effect  of  chemical  combinations,  that  it  seems  by 
farjnost  convenient  not  to  separate  Aerology  from  Chemistry,  but 
to  regard  it  as  a  subordinate  section  or  subdivision  of  chemical 
science. 

8.  In  solid  and  liquid  substances,  the  powers  of  attraction  and  re- 
pulsion counterbalance  each  other ;  while  the  latter  predominates 
in  gaseous  bodies.     Some  have  supposed  solidity  to  result  from 
the  preponderance  of  the  force  of  attraction  over  the  force  of  repul- 
sion ;  but  this  opinion  seems  incompatible  with  the  well-known 
fact  of  the  expansion  of  water  when  it  becomes  solid.     This  and 
some  other  phenomena  of  a  similar  description,  clearly  show  that 
the  action  of  a  repulsive  force  is  not  less  obvious  in  solids  than 
in  fluids.     They  probably  differ  more  in  the  arrangement  of  their 
particles,  than  in  the  manner  in  which  those  particles  are  united. 

9.  The  peculiar  province  of  Chemistry,  as  might  be  inferred 
from  the  preceding  observations,  is  the  study  of  the  Attraction  of 
Composition,  or  the  investigation  of  the  properties  of  bodies,  not 
as  respects  their  organization,  mechanical  construction,  form,  or 
consistence,  but  with  a  view  to  the  discovery  of  their  molecular 
composition,  or  the  nature  and  mode  of  union  of  their  component 
particles.     Hence  there  must  necessarily  be  a  wide  distinction 
between  mechanical  and  chemical  combination.     Any  substances 
may  be  mechanically  combined  by  mere  mixture,  which  occasions 
no  destruction  or  essential  alteration  of  the  sensible  properties  of 
the  mixed  bodies  :  for  the  compound  formed  by  the  union  of  two 
or  more  substances  which  have  no  chemical  action  on  each  other, 
will  always  exhibit  their  joint  properties,  modified,  perhaps,  but 
not  destroyed  by  their  commixture.     The  effect  of  chemical  com- 
bination is   very   different,   for  bodies  chemically   united   often 
become    completely   deprived   of  the  peculiar   properties    they 
previously  possessed,  and  manifest  new  and  sometimes  very  ex- 
traordinary powers,  totally  different  from  those  of  their  constituent 
parts. 

10.  "  If  water  be  added  to  water,  or  salt  to  salt,  the  effect  is  an 
increase  of  quantity,  but  no  change  of  quality.     In  this  case,  the 
mutual  action  of  the  particles  is  entirely  mechanical.     Again,  if  a 
blue  powder  and  a  yellow  one,  each  perfectly  dry,  be  mixed  and 
well  shaken  together,  a  green  powder  will  be  produced ;  but  this 
is  a  mere  effect  arising  in  the  eye,  from  the  intimate  mixture  of 

In  what  relation  to  chemistry  may  we  properly  consider  the  department 
of  aerology  ?  Why  ? 

What  are  the  relative  intensities  of  attraction  and  of  repulsion  in  solids, 
liquids,  and  aeriform  bodies? 

What  is  the  peculiar  province  of  chemistry  ? 

What  is  the  most  important  difference  between  bodies  mechanically 
mixed  and  those  chemically  combined  ? 


12  CHEMISTRY. 

the  yellow  and  blue  light,  separately  and  independently  reflected 
from  the  minute  particles  of  each ;  and  the  proof  is  had  by  exa- 
mining the  mixture  with  a  microscope,  when  the  yellow  and  blue 
grains  will  be  seen  separate,  and  each  quite  unaltered.  If  the 
same  experiment  be  tried  with  coloured  liquids,  which  are  sus- 
ceptible of  mixing  without  chemical  action,  a  compound  colour  is 
likewise  produced,  but  no  examination  with  magnifiers  is  in  that 
case  sufficient  to  detect  the  ingredients;  the  reason  obviously  be- 
ing, the  excessive  minuteness  of  the  parts,  and  their  perfect  inter- 
mixture, produced  by  agitating  two  liquids  together. 

11.  "From  the  mixture  of  two  powders,   extreme   patience 
would  enable  any  one,  by  picking  out  with  a  magnifier  grain  after 
grain,  to  separate  the  ingredients.     But  when  liquids  are  mixed, 
no  mechanical  separation  is  any  longer  practicable ;  the  particles 
are  so  minute  as  to  elude  all  search.     Yet  this  does  not  hinder  us 
from  regarding  such  a  compound  as  still  a  mere  mixture,  and  its 
properties  are  accordingly  intermediate  between  those  of  the  li- 
quids mixed.  But  this  is  far  from  being  the  case  with  all  liquids. 

12.  "  When  a  solution  of  potash,  for  example,  and  another  of 
tartaric  acid,  each  perfectly  liquid,  are  mixed  together  in  proper 
proportions,  a  great  quantity  of  solid  saline  substance  falls  to  the 
bottom  of  the  containing  vessel,  which  is  quite  different  from  pot- 
ash or  tartaric  acid,  and  the  liquid  from  which  it  subsided  offers 
no  indications  by  its  taste  or  other  sensible  qualities  of  the  ingre- 
dients mixed,  but  of  something  totally  different  from  either.     It  is 
evident  that  this  is  a  phenomenon  widely  different  from  that  of 
mere  mixture  ;  there  has  taken  place  a  great  and  radical  change 
in  the  intimate  nature  of  the  ingredients,  by  which  a  new  sub- 
stance is  produced  which  had  no  existence  before  ;  and  it  has  been 
produced  by  the  union  of  the  ingredients  presented  to  each  other, 
for  when  examined,  it  is  found  that  nothing  has  been  lost,  the 
weight  of  the  whole  mixture  being  the  sum  of  the  weights  mixed. 
Yet  the  potash  and  the  tartaric  acid  have  disappeared  entirely, 
and  the  weight  of  the  new  product  is  found  to  be  exactly  equal  to 
that  of  the  tartaric  acid  and  potash  employed,  taken  together, 
abating  a  small  portion  held  in  solution  in  the  liquid,  which  may 
be  obtained  however  by  evaporation.     They  have  therefore  com- 
bined, and  adhere  to  one  another  with  a  cohesive  force  sufficient 
to  form  a  solid  out  of  a  liquid  ;  a  force  which  has  been  called  into 
action  by  merely  presenting  them  to  each  other  in  a  state  of  solu- 
tion."* 

How  does  it  appear  that  blue  and  yellow  powders,  producing  a  green 
mixture  retain  their  respective  qualities  ? 

In  what  respect  does  the  case  of  two  coloured  liquids,  susceptible  only 
of  mixture,  and  not  of  chemical  composition,  differ  from  that  of  two  pow- 
ders? 

Give  an  example  of  an  entire  change  of  properties  in  two  liquids  by 
their  mutual  actions  when  mixed  together. 

*  Hersehell's  Discourse  on  the  Study  of  Natural  Philosophy,  pp  297, 298. 


MODERN  DISCO VEIES.  13 

13.  As  it  is  the  object  of  Chemistry  to  determine  the  composition 
of  different  substances,  therefore  if  we  could  reduce  all  bodies  to 
their  elementary  principles,  and  discover  the  proportions  in  which 
these  principles  must  be  combined  in  order  to  recompose  such  bo- 
dies, the  science  of  Chemistry  would  be  complete.     This,  how- 
ever, is  far  from  being  the  case,  notwithstanding  the  extraordinary 
discoveries  that  have  rewarded  the  labours  of  those  philosophers 
who  have  paid  attention  to  this  important  branch  of  knowledge. 

14.  But  though  we  allow  that  much  remains  to  be  achieved  by 
future  experimentalists  ere  Chemistry  can  be  said   to  make  any 
near  approaches  to  perfection,  yet  it  must  be  admitted,  that  the 
improvements  which  have  taken  place  in  this  science  in  our  own 
times  are  of  no  common  importance,  since  its  first  principles  have 
been  fixed  on  the  firm  basis  of  experiment,  and  a  luminous  sys- 
tem, founded  on  facts,  has  superseded  those  obscure  and  hypo- 
thetical  speculations  which  occur  in  the  writings  of  the  older 
chemical  authors. 

15.  Among  the  most  important  discoveries  of  modern  philoso- 
phers, we  may  reckon  those  which  relate  to  that  inherent  ten- 
dency which  matter  possesses  to  form  new  combinations.     This 
property  of  matter  gives  rise  to  many  of  those  operations  of  nature 
which  we  view  without  surprise,  only  because  they  are  common  ; 
and  it  is  not  less  concerned  in  several  of  the  most  striking  and  ex- 
traordinary phenomena  of  nature  and  art.    Thus  when  we  procure 
light  or  heat  by  burning  any  combustible  substance,  as  for  instance 
wood,  chemical  action  takes  place  between  the  inflammable  mat- 
ter contained  in  the  wood,  and  part  of  the  air  of  the  room  in  which 
the  wood  is  burned ;  in  consequence  of  which,  a  new  kind  of  air 
is  formed,  the  greater  part  of  which  flies  off  with  the  smoke. 
The  respiration  of  animals  affords  another  instance  of  chemical 
action.     When  air  is  taken  into  the  lungs,  a  part  of  it  combines 
with    something   which    separates   from   the  blood ;    in   conse- 
quence of  which  combination,   the  air  becomes   altered  in   its 
properties,  as  must  be  obvious  to  every  one  who  considers  that 
the   atmosphere   of  a   crowded    apartment,   not   properly   venti- 
lated, is  soon  rendered  so  noxious  as  to  occasion  considerable 
inconvenience,  and  even  faintness,  to  those  whose  constitutions 
are  delicate. 

16.  On  taking  a  survey  of  the  various  bodies  around  us,  we 
may  observe,  that  some  among  them,  which  we  reckon  inert,  be- 
cause from  the  influence  of  habit  or  oth<r  causes  they  make  but  a 
slight  impression  on  our  senses,  are  yet  endowed  with  active 
poweis  or  properties,  which  render  them  capable  of  producing  re- 

What  power  might  enable  chemists  to  render  their  science  complete  ? 

What  constitutes  the  chief  difference  between  the  chemistry  of  modern 
and  that  of  ancient  times  ? 

What  chemical  principles  may  be   considered  as  among  the  most  im- 
portant discoveries  of  modern  philosophers  ? 

How  are  those  principles  exemplified  in  the  operations  of  nature? 

How  may  their  operation  be  made  sensible  ? 
B 


14  CHEMISTRY. 

mark-able  changes  in  other  bodies.  Thus  water,  which  is  insipid 
to  the  tongue,  and  which  in  its  operation  on  living  animals  and 
vegetables  acts  slowly  and  almost  imperceptibly,  will  yet,  if 
placed  in  contact  with  a  lump  of  salt  or  sugar,  speedily  reduce 
either  from  the  solid  to  the  liquid  slate.  Atmospheric  air,  though 
it  is  necessary  for  the  support  of  animal  and  vegetable  existence, 
and  gives  rise  to  scarcely  any  sensations  but  such  as  depend  on 
variations  of  temperature,  yet  this  widely-extended  gaseous  body 
by  its  union  with  other  substances,  sometimes  produces  the  most 
striking  phenomena.  Thus  the  explosion  of  fire-damp  in  coal- 
mines can  only  happen  when  the  inflammable  gas  so  called,  is 
mixed  with  a  certain  portion  of  common  air. 

17.  One  of  the  most  obvious  modes  of  distinguishing  bodies  is 
that  which  depends  on  their  different  degrees  of  density  ;  whence 
the  arrangement  of  substances  into  the  respective  classes  called 
solids,  liquids,  and  gases,  already  noticed.  But  these  distinctions 
cannot  be  advantageously  employed  as  the  basis  of  a  chemical 
classification  of  natural  bodies,  for  reasons  which  have  been  al- 
ready stated.     Hence  some  other  mode  of  discrimination  and  ar- 
rangement becomes  requisite,  and  such  a  one  may  be  most  properly 
derived  from  considering  the  chemical  relations  of  different  kinds 
of  matter,  and  the  products  derived  from  their  action  on  each 
other. 

18.  There  are  some  bodies  which  by  no  known  mode  of  treat- 
ment, without  addition,  can  be  made  to  form  more  than  one  species 
of  matter;  for  however  they  may  be  divided  or  subdivided,  each 
particle  still  possesses  the  same  chemical  properties  with  the 
common  mass,  from  which  it  was  taken.  There  are  comparatively 
but  few  bodies  presented  to  us  by  nature  in  this  isolated  state  ; 
among  the  number  may  be  mentioned,  as  examples,  gold  and  the 
diamond.     These,  together  with  all  other  hitherto  undecomposed 
bodies,  must  in  the  present  state  of  chemical  science  be  considered 
as  elementary  or  simple  substances.     Were  it  practicable  to  pro- 
cure and  exhibit  all  the  elements  of  bodies  in  a  detached  form, 
and  to  trace  the  various  compounds  resulting  from  their  union, 
Chemistry  would  have  attained  perfection,  and   no  object  of  in- 
quiry would  remain  for  future  experimentalists.     But  notwith- 
standing the  great  acquisition  of  knowledge  derived  from  the  dis- 
coveries of  our  contemporaries,  they  have  by  no  means  enabled 
us  to  determine  the  boundaries  of  the  field  of  science,  but  merely 
to  form  some  conjectural  ideas  concerning  its  vast  extent. 

9,  No  correct  general  knowledge  of  the  nature  and  properties 

How  may  we  illustrate  the  chemical  efficacy  of  natural  substances  gene- 
rally supposed  inert? 

What  is  one  of  the  readiest  modes  of  distinguishing  bodies? 

On  what  are  the  discrimination  and  arrangement  of  bodies  for  chemical 
purposes  to  be  founded  ? 

What  is  the  natural  state  of  most  bodies  in  regard  to  their  composition? 

What  exceptions  are  found  to  the  general  law  in  regard  to  a  distinct 
and  isolated  condition? 


SIMPLE  BODIES. 

of  different  substances  can  be  acquired  without  instituting  compari- 
sons between  them,  whence  we  may  discover  the  various  points  of 
similitude  or  contrast  among  them,  which  will  enable  us  to  arrange 
them  in  groups  or  classes,  bearing  certain  relations  to  each  other. 

20.  For  the  purposes  of  chemical  inquiry,  the  most  obviously 
convenient  arrangement  of  bodies  is  that  in  which  they  are  classed 
according  to  their  composition,  placing  the  simple  bodies  first  in 
order,  and  then  the  compounds  arising  from  the  various  combina- 
tions of  the  former. 

21.  According  to  the  ancient  philosophers,  the  simple  bodies  or 
elementary  principles  from  which  all  the  varieties  of  matter  are 
composed^  were  but  four,  namely,  Fire,  Air,  Water,  and  Earth. 
This  notion,  after  having  for  ages  formed  a  part  of  the  creed  of 
the  learned,  has  been  completely  exploded  by  the  light  of  modern 
science,  though  it  is  not  yet  extinct  among  the  vulgar.     The 
alchemical  writers  of  the  middle  ages  added  to  these  principles 
some  others,  as  Salt,  Sulphur,  and  Mercury;  to  which  terms, 
however,  they  attached  ideas  very  different  from  those  that  belong 
to  them  at  present,  and  into  the  nature  of  which  we  shall  not  stop 
to  inquire. 

22.  Some  of  the  alleged  elements  of  the  older  chemists  are  now 
known  to  exist  only  in  imagination,  and  others  are  ascertained  to 
be  by  no  means  simple  substances  :  thus  air  is  found  to  consist  of 
two   different  elastic  fluids  or  gaseous   bodies,  which    may   be 
separated   by  various  processes,  and  exhibited  apart  from  each 
other.    Water  also  has  been  ascertained  to  be  a  compound  which 
may  be  analyzed  or  decomposed,  so  as  to  produce  two  distinct 
kinds  of  gas,  which  may  be  separately  collected,  and  when  again 
mixed  together  in  proper  proportions,  they  may  be  made  to  form 
water  by  their  union. 

23.  Other  bodies,  formerly  esteemed  simple,  have  yielded  to 
the  analytical  processes  of  modern  chemistry  ;  but  there  is  a  cer- 
tain number  of  substances  which  either  in  the  state  in  which  they 
are  presented  to  us  by  nature,  or  as  they  are  procured  in  various 
operations  by  art,  have  hitherto  resisted  all  attempts  at  further  de- 
composition, and  which  therefore,  as  before  stated,  must  be  re- 
garded as  simple  substances.     Their  number  is  not  very  great, 
amounting  to  about  fifty-four,  and  it  is  not  unlikely  that  the  future 
researches  of  chemists  may  demonstrate  some  of  these  bodies  to 
be  compounds;  at  the  same  time,  it  is  probable  that  additions 
may  be  made  to  the  class  of  elementa^  substances  in  consequence 

How  is  a  correct  knowledge  of  the  nature  and  properties  of  bodies  to  be 
acquired  ? 

In  what  order  is  it  most  convenient  to  arrange  bodies  for  chemical  pur- 
poses ? 

How  many  simple  bodies  were  admitted  by  the  ancients  ? 

What  additions  to  the  number  were  made  by  the  alchemists? 

What  has  modern  science  proved  in  regard  to  the  supposed  elementary 
character  of  air  and  water  ? 

What  number  of  bodies  are  now  considered  simple  ? 


16  CHEMISTRY. 

of  future  discoveries,  several  of  those  now  admitted  into  this  class 
having  become  known  to  us  but  very  recently. 

24.  Some  of  these  elementary  bodies  are  widely  and  abundant- 
ly dispersed  throughout  the  three  kingdoms  of  nature,  either  alone 
or  in  a  state  of  composition,  while  others  appear  to  be  of  very 
rare  occurrence,  or  at  least  they  have  hitherto  been  met  with  only 
in  small  quantities  and  in  a  few  situations.     The  whole  of  the 
elementary  substances  may  be  arranged  in  two  divisions  :  the  first 
comprehending  those  which  are  not  of  a  metallic  nature,  the  entire 
number  of  which  now  known  amounts  to  only  thirteen ;  the  re- 
maining forty-one  elementary  bodies  are  all  regarded  as  metals, 
though  some  of  them  exhibit  properties  differing   considerably 
from  those  which  characterize  gold,  silver,  mercury,  lead,  iron,  and 
other  bodies,  to  which  the  designation  of  metals  was  originally 
applied. 

25.  The  following  table  exhibits  a  list  of  all  the  elementary  or 
simple  bodies  hitherto  discovered,  divided  into  these  two  classes, 
namely,  the  non-metallic  elements  and  the  metals;  to  which  are 
annexed  the  names  of  those  chemists  by  whom  they  were  dis- 
covered, or  by  whom  their  elementary  nature  was  first  ascertained, 
and  the  date  of  the  discovery. 

TABLE  OF  SIMPLE  SUBSTANCES. 

I.  Non-metallic  Elements. 
Discover. 

Dr'  Priestly>  in  England;    and      71774 
Scheele,  in  Sweden      ...       S 

2  Chlorine  ....    Scheele,  in  Sweden 1774 

3  Iodine Courtois,  in  France 1811 

4  Bromine  ....    Balard,  in  France 1826 

f"  Properties  first  accurately  investi- 

5  Fluorine  .  .  .   •<      gated  by  Scheele;  but  it  has  never 

C.      been  exhibited  in  a  separate  state. 

6  Hydrogen   .  .  .    Cavendish,  in  England     ....     1766 

7  Nitrogen     ...   Dr.  D.  Rutherford,  in  Scotland       .     1772 

8  Carbon 

9  Boron Sir  H.  Davy,  in  England      .     .     .     1807 

10  Silicon     ....  Berzelius,  in  Sweden  ....  1824 

11  Phosphorus   .  .  Brandt,  at  Hamburgh  ....  1669 

12  Sulphur 

13  Selenium    .  .  .  Berzelius,  in  Sweden  ....  1818 

Into  how  many  and  what  divisions  are  simple  bodies  at  present  distin 
guished? 

What  is  the  number  of  non-metallic  elements  ? 

By  whom  and  at  what  period  was  the  existence  of  oxygen  discovered  ? 
Bromine  ?  Chlorine  ?  Iodine  ?  Nitrogen  ? 

Who  investigated  the  properties  of  fluorine? 

Who  discovered  hydrogen  ?   Carbon  ?   Boron  ?   Silicon  ?   Phosphorus  1 
Selenium  ? 


TABLE  OF  SIMPLE  SUBSTANCES. 


14  Potassium  , 

15  Sodium    .  . 

16  Lithium  .  . 

17  Baryum   .  . 

18  Strontium    . 

19  Calcium  .  . 

20  Magnesium 

21  Aluminum  . 

22  Glucinum   . 

23  Yttrium  .  . 

24  Zirconium  . 

25  Thorium  .  . 

26  Cerium    .  . 

27  Tellurium  . 


28  Arsenic    .  . 

29  Antimony   . 

30  Chromium  . 

31  Vanadium  .  , 

32  Uranium 

33  Molybdenum 

34  Tungsten    .  , 

35  Columbium   . 


36  Titanium     , 

37  Iron    .... 

38  Manganese 

39  Nickel     .  , 

40  Cobalt  .  .  , 

41  Zinc  .... 

42  Cadmium  . 

43  Lead     .  .  . 

44  "Tin 

45  Copper     .  . 


Discoverers. 
II.  Metals. 
H.  Davy,  in  England 


Date  of 
Discovery 

1807 


f 


C  Oxide  discovered  by  Arfvedson,  in  ")  1Q1Q 
1     Sweden       .     .    '      .         .     .     .  j 1818 


Sir  H.  Davy,  in  England      .     .     .     1808 


.    Bussy,  in  France 1829 

.    Wohler,  in  Germany 1828 

C  Oxide  discovered  by  Vauquelin,  in  "> 

(      France $ 

C  Oxide  discovered   by   Gadolin,  in  } 

£      Sweden j 

,    Berzelius,  in  Sweden 1824 

.    Berzelius 

,    Mosander,  in  Sweden       ....     1804 
Klaproth,  at  Berlin 1797 

T Appears  to   have   been  known   to"^ 
Paracelsus,  in  the  16th  century;  it^o-* 
but  first  accurately  examined  by  j     ' 
Geo.  Brandt,  in  Sweden     .     .     J 
.    Known  to  Basil  Valentine    .     about  1450 
.    Vauquelin,  in  France        ....     1797 
.    Sefstrom  and  Berzelius,  in  Sweden     1830 

.    Klaproth,  at  Berlin 1789 

rScheele,  in  Sweden 1778 

<  Reduced  to  the  metallic  state  by  7  i^o-» 

(      Hielm        S 

.    MM.  D'Elhuyarts,  in  Spain       .     .     1781 
("Oxide  discovered  by  Hatchett,  in  ^ 
J       England;    and  by  Ekeberg,  in  C 1801 

)      Sweden J 

LReduced  by  Berzelius  ....  1824 
.  Vauquelin,  in  France  ....  1796 
.  Known  from  time  immemorial 

.    Gahn,  in  Sweden 1774 

.    Bergman,  in  Sweden 1775 

.    Brandt,  in  Sweden 1733 

.    Henckel  mentions  its  reduction  in       1791 
.    Stromeyer  in  Germany     ....     1817 
.    Known  from  time  immemorial, 
Do. 
Do. 


What  metallic  bodies  have  been  discovered  by  Sir.  H.  Davy  ?     By  what 
philosopher  was  aluminum  discovered  ?     How  early  was  arsenic  known  ? 
Which  of  the  metals  have  been  known  from  the  earliest  ages  of  history  ? 
IIo\v  lung  has  zinc  been  known  as  a  rlitinct  metal  ? 

B2 


18  CHEMISTRY. 

Discoverer, 

46  Bismuth  ....  Mentioned  by  Geo.  Agricola     about  1530 

47  Mercury  ....  Known  from  time  immemorial. 

48  Silver    .....  Do. 

49  Gold     .....  Do. 

50  Platina    .  .  .  ^**   Assay-master 


51  Palladium  ...   Dr.  Wollaston,  in  England  .     .     .     1803 

52  Rhodium     .  .  .   The  same        ........     1804 

54  Osmium  :::   }  Tenant,  in  England     .....     1803 

27.  As  some  of  these  elementary  bodies  enter  into  the  composi- 
tion of  a  vast  variety  of  substances  of  common  occurrence,  and 
as  it  is  impossible  intelligibly  to  describe  chemical  pbenomena 
without  the  frequent  mention  of  them,  or  allusion  to  their  proper- 
ties and  modes  of  action,  some  short  notices  of  them  may  here  be 
advantageously  introduced,  previously  to  a  review  of  the  laws  of 
chemical  affinity,  and  a  more  extensive  description  of  the  simple 
bodies  in  general,  and  of  the  most  important  compounds  arising 
from  their  relative  action  upon  each  other.   We  shall  thus  avoid  the 
necessity  of  repeated  explanations  of  the  nature  of  these  bodies  each 
time  they  are  mentioned,  or  the  still  greater  inconvenience  of 
referring  to  the  properties  and  effects  of  substances  with  which 
the  reader  may  be  supposed  to  be  unacquainted. 

28.  Among  the  thirteen  non-metallic  elements  there  are  some 
which  at  all  common  temperatures  exist  only  in  the  gaseous  state, 
while  the  others  at  moderately  low  temperatures  are  solids.    The 
first  and  most  important  of  the  elementary  bodies  is  that  called 
OXYGEN,  from  two  Greek  words,  denoting  the  power  of  producing 
acids,  because  it  was  formerly  thought  to  be  the  universal  acidify- 
ing principle,  though  it  is  now  known  that  there  are  many  acids 
in  which  oxygen  is  not  contained.     One  of  the  grand  characteris- 
tic properties  of  this  gaseous  element  is  that  of  being  a  most 
powerful   supporter   of  combustion,  so  that   most   inflammable 
bodies  burn  in  it  rapidly  and  brilliantly.     Its  more  peculiar  pro- 
perties will  be  subsequently  described  ;  and  we  shall  only  add 
here  that  it  unites  with  all  other  elementary  substances  (except 
possibly  fluorine),  and  with  many  of  them  in  various  proportions. 

29.  NITROGEN  OR  AZOTE  is  also  a  gaseous  body,  the  mixture  of 
which  with  oxygen  in  certain  proportions  constitutes  atmospheric 
or  common  air.     The  name  azote,  derived  from  the  Greek,  im- 
plies its  being  improper  for  the  purpose  of  respiration,  as  animals 
confined  in  this  gas  soon  die.    It  is  therefore  owing  to  the  oxygen 

By  whom  and  at  what  period  was  platina  discovered  ?  In  what  two 
states  do  the  non-metallic  bodies  exist  ?  What  is  the  origin  of  the  term 
oxygen  ?  What  is  one  of  the  characteristic  properties  of  oxygen  ? 

How  extensive  is  its  power  of  combining  with  other  elementary  bodies  ? 

In  what  state  does  nitrogen  exist  ? 

Into  what  well  known  fluid  does  it  enter  as  a  constituent  ? 

Why  is  it  called  azote  ?     Whence  is  the  term  nitrogen  derived  ! 


CHLORINE. 

containedjn  atmospheric  air  that  it  is  capable  of  supporth,^ 
life,  for  none  of  the  higher  classes  of  animals  can  exist  longv^ 
kind  of  air  which  does  not  contain  oxygen. 

30.  The  term  Nitrogen  has  been  applied  to  the  gas  now  undeV' 
notice,  in  consequence  of  its  being  found  to  be  a  constituent  part 
of 'nitric  acid,  or  as  it  is  vulgarly  called,  aqua  fortis,  which  is  a 
chemical  compound  containing  a  very  large  proportion  of  oxygen 
united   to   the   nitrogen.     There   are   also  other  compounds  of 
oxygen   with  nitrogen,   among   which   may  be  mentioned  that 
sometimes  called  nitrous  oxide,  and  which,  though  it  contains 
more  oxygen  than  atmospheric  air,  may  yet  be  breathed  for  a 
time  with  safety;  but  it  produces  very  remarkable  effects  when 
thus  used,  generally  occasioning  a  state  of  excitement  somewhat 
similar  to  that  caused  by  drinking  wine  or  spirits,  and  hence  it 
has  been  popularly  named  intoxicating  or  laughing  gas.  Nitrogen 
enters   largely  into  the  composition   of  most  kinds  of  animal 
matter. 

31.  HYDROGEN   is   likewise   a  gas,  being   that   which   when 
combined  with  oxygen  forms  water,  as  its  name,  which  is  derived 
from  the  Greek,  implies.    .It  was,  when  first  discovered,  called 
phlogiston,  and    inflammable   air.     The  former  of  these  terms 
was  attached  to  it  in  consequence  of  an  erroneous  opinion,  at  one 
period  generally  adopted  by  chemists,  that  all  metals  were  com- 
posed  of  various  kinds  of  calces  or  earths,  each   respectively 
united  to  an  inflammable  principle  named  phlogiston.    Now  as  it 
was  observed  that  when  any  metal  becomes  dissolved  in  a  diluted 
acid,  as  when  iron  or  zinc  are  thus  treated  with  sulphuric  acid 
and  water,  inflammable  air  was  always   given   off  during  the 
process,  it  was  conjectured  that  the  air  in  question  was  derived 
from  the  metal ;  though  it  is  now  known  that,  in  the  case  pro- 
posed, it  arises  from  the  decomposition  of  the  water  with  which 
the  acid   is  diluted,  and  that  this  sort  of  air  never  makes  its 
appearance  in  the  course  of  such  metallic  solutions,  unless  water 
or  some  other  body  containing  hydrogen  be  present.     This  gas, 
though  highly  inflammable  when  mixed  with  oxygen,  and  some 
other  simple  and  compound  gases,  yet  is  incapable  of  supporting 
combustion,  for  if  a  burning  body,  as  a  lighted  candle  or  match, 
be  introduced  into  it,  the  flame  will  be  immediately  extinguished. 

32.  Hydrogen  enters  into  combination  with  most  other  sub- 
stances, producing  many  remarkable  compounds,  among  which 
may  be  mentioned  that  formed  by  its  union  with  nitrogen ;  the 
result  of  which-ls  an  alkaline  gas,  formerly  called  volatile  alkali, 

In  what  other  form  besides  that  of  atmospheric  air  may  nitrogen  be 
inhaled  ? 

Into  what  class  of  organised  bodies  does  nitrogen  enter  ? 
What  is  the  meaning  of  the  word  hydrogen  ? 
By  what  name  was  it  called  at  the  time  of  its  discovery 
From  what  error  did  this  application  of  the  name  phlogiston  proceed  ? 
What  more  recent  observation  has  enabled  chemists  to  correct  the  error  ? 
What  is  the  power  of  hydrogen  in  regard  to  combustion? 


'SO 


CHEMISTRY. 


and  now  ammonia.  This  compound  which  at  common  tempera- 
tures exists  only  in  the  state  of  gas,  is  rapidly  absorbed  by  water 
or  spirit  of  wine,  communicating  to  it  a  peculiar  pungent  odour, 
with  which  most  persons  are  familiar,  as  belonging  to  spirit  of 
hartshorn  and  smelling  salts. 

33.  CHLORINK  is  the  last  of  the  simple  bodies  existing  in  a  gaseous 
state  at  common  temperatures  ;  but,  while  those  already  mentioned 
are  not  only  transparent  but  colourless,  this  gas  exhibits  a  yellow- 
ish-green tint,  whence  its  name  chlorine.*  'It  was  originally  ob- 
tained, by  Scheele,  from  the  decomposition  of  muriatic  acid,  or 
spirit  of  salt,  in  which  he  found  it  combined  with  hydrogen,  then 
called  phlogiston  ;  and  therefore  he  gave  to  the  newly-obtained 
gas  the  name^  of  dephlogisticated  marine  acid."     It  was  subse- 
quently supposed  to  be  a  compound  of  muriatic  acid,  and  oxygen  ^ 
but  Sir  H.  Davy  ascertained  its  real  nature,  and  gave  it  its  present 
name. 

34.  Chlorine  unites  with  many  other  simple  and  compound 
bodies,  forming  with  several  of  them  acids;  and  in  other  respects 
it  exhibits   chemical  properties  analogous  to  those  of  oxygen, 
being  like  that  gas  a  supporter  of  combustion.      It  is  largely  dis- 
persed throughout  nature,  but  always  in  a  state  of  combination, 
as  in  sea-water  and  rock-salt,  or  that  procured  from  brine  springs, 
in  which  it  is  united  with  the  metal  sodium.     This  gas  is  by  no 
means  adapted  for  respiration,  and  when  mixed  with  much  atmos- 
pheric air  it  still  proves  highly  irritating,  provoking  cough  and 
defluxion  from  the  nostrils.     As  it  combines  rapidly  with  many 
other  gases,  it  has  been  found  useful  to  purify  air  loaded  with 
infectious  miasmata.     It  is  on  this  account  that  the  chloride  of 
lime,  in  solution,  is  used  to  sprinkle  the  floors  and  walls,  of 
rooms,  and  to  purify  clothes  and  other  articles,  which  have  been 
tainted  by  putrid  or  infectious  vapours.      Chlorine  has  also  a 
powerful  effect  in  destroying  vegetable  colours,  and  the  chloride 
of  lime  is  therefore  extensively  used  in  the  process  of  bleaching 
linen  cloth  and  other  substances. 

35.  The  four  preceding  bodies,  oxygen,  hydrogen,  nitrogen, 
and  chlorine,  exist  at  common  temperatures  and  pressures  only 

What  may  be  mentioned  as  among  the  remarkable  compounds  of  hy- 
drogen ? 

By  what  properties  is  that  compound  familiarly  known  ? 

What  method  was  employed  by  Scheele  for  procuring  chlorine  ? 

What  name  did  he  apply  to  it  I 

What  was  afterwards  supposed  to  be  its  nature  ? 

Who  investigated  its  character  and  gave  it  the  present  name  ? 

What  properties  does  it  exhibit  in  common  with  oxygen  ? 

How  does  chlorine  exist  in  nature  ? 

What  are  among  its  remarkable  properties  ? 


*  Chlore  in  French,— from  the  Greek  %^«»s,  the  green  colour  of  young 
herbage. 


.. 


SILICON.  2J 


as  gas.  There  are  other  suhstances,  as,  for  instance,  carbon 
(charcoal),  and  the  more  rare  bodies,  called  silicon  and  boron, 
which  are  found  only  in  the  solid  state;  and  some,  like  iron  and 
most  of  the  metals,  though  usually  solid,  become  liquefied  at 
respectively  various  temperatures  ;  and  there  is  still  another  class 
of  bodies  capable  of  existing  under  the  three  several  forms  of 
aggregation.  Among  these  last  are  sulphur,  phosphorus,  and 
the  substances  called  bromine,  iodine,  and  selenium,  which  are 
of  less  frequent  occurrence. 

36.  CARBON  is  a  solid  body,  hitherto  undecomposed  and  there- 
fore  supposed  to  be  elementary,  which  enters  largely  into  the 
composition  of  most  substances  belonging  to  the  animal  and  vege- 
table kingdoms,  and  which  also  forms  the  basis  of  many  of  the 
combustible  minerals,  as  bitumen,  coal,  plumbago,  and  amber. 
In  the  form  of  charcoal,  procured  by  charring,  or  distilling  with- 
out the  access  of  air,  wood  and  some  other  substances,  carbon  is 
obtained  in  a  separate  state,  or  merely  intermixed  with  small 
portions  of  earths  or  salts ;  and  it  exists  in  a  state  of  the  greatest 
purity  in  the  diamond ;   for  it  has  been  ascertained  by  chemical 
investigation,  that  the  diamond,  when  exposed  to  a  very  high 
temperature,  and  especially  if  confined  in  oxygen  gas,  will  burn 
like  charcoal,  exhibiting  the  same  product ;   that  gem  consisting 
entirely  of  crystallized  carbon. 

37.  With  most  of  the  simple  substances  carbon  constitutes  a 
variety  of  compounds,  among  the  most  important  of  which  are 
those  arising  from  its  union  with  oxygen,  with  which  it  forms 
both  an  oxide  and  an  acid  :    the  latter,  called  carbonic  acid,  is 
the  gaseous  body  formerly  known  by  the  name  of  fixed  air,  which 
is  abundantly  produced  in  the  combustion  of  vegetable  matter,  in 
the  respiration  of  animals,  and  in  other  processes.      In  conse- 
quence of  its  strong  affinity  for  oxygen,  carbon,  or  rather  sub- 
stances containing  it,  are  generally  used  for  the  purpose  of  reduc- 
ing iron  and  other  metals  from  their  ores,  in  which   they   are 
frequently   combined  with  oxygen.      The  combinations  of  this 
body  with  hydrogen  are  extremely  numerous,  forming  the  bases, 
of  vinous  spirits,  oils,  resins  and  a  great  variety  of  other  vegeta- 
ble products. 

38.  SILICON  is  never  met  with  in  nature  in  an  uncombined  state, 

What  three  substances  have  been  separately  procured  only  in  the  solid 
state  ? 

What  substances  assume  all  the  three  forms  of  matter  under  different 
circumstances  ? 

fn  how  many  departments  of  nature  is  carbon  distributed  ? 

In  what  form  does  it  exist  in  the  greatest  purity  ? 

How  is  this  proved  ? 

What  different  compounds  does  it  form  with  oxygen  ? 

By  what  name  was  carbonic  acid  formerly  known  ? 

Why  is  carbon  used  in  the  process  of  smelting  metallic  ores? 

What  are  some  of  the  compounds  of  carbon  with  hydrogen  ? 

How  is  silicon  found  in  nature  ? 


CHEMISTRY. 

but  by  its  union  with  oxygen  it  forms  silica,  or  siliceous  earth, 
which  in  the  various  states  of  flint,  quartz,  rock  crystal,  and  other 
analogous  bodies,  is  dispersed  in  great  abundance  throughout  the 
mineral  kingdom.  This  substance  when  pure  is  a  dark  brown 
powder,  which  when  first  discovered  was  supposed  to  be  of  a 
metallic  nature  ;  but  as  it  exhibits  none  of  the  lustre  of  a  metal, 
and  is  a  nonconductor  of  electricity,  it  has  with  propriety  been 
placed  in  the  class  of  non-metallic  elementary  bodies.  It  unites 
with  several  other  substances,  forming  compounds,  the  most  im- 
portant of  which,  next  to  the  oxide  of  silicon,  (silica,)  is  the  pro- 
duct of  its  union  with  fluorine. 

39.  BORON  is  the  basis  of  the  acid  called  boracic  acid,  which 
in  combination  with  soda  or  mineral  alkali,  produces  the  saline 
substance  named  borax,'  frequently  used  both  in  medicine  and 
the  arts.     Boron  is  an  olive-brown  powder,  destitute  of  taste  or 
smell,  which  enters  into  union  with  some  of  the  metals  and  other 
elementary  bodies ;  but  its  combinations  are  of  little  importance, 
except  that  which  it  forms  with  oxygen  (boracic  acid.) 

40.  SULPHUR  is  one  of  the  few  elementary  substances  which  are 
found  in  nature  in  an  uncombined  state ;  and  it  also  often  occurs 
in  union  with  other  substances.  It  is  met  with  in  large  quantities 
in  the  neighbourhood  of  volcanos  ;  and  being  produced  abundant- 
ly in  the  island  of  Sicily,  it  is  brought  as  an  article  of  commerce 
from  the  Mediterranean.     This  substance,  hitherto  undecomposed, 
and  therefore  regarded  as  elementary,  occurs  in  two  forms,  that 
of  a  light  yellow  powder  called  flowers  of  sulphur,  and  that  of  a 
compact  solid  of  a  greenish-straw  colour,  sometimes  called  roll 
sulphur.      The  general  properties  of  sulphur  in  both  these  forms 
are  well  known. 

41.  SULPHUR  combines   with   most   other  bodies,   forming  a 
variety  of  compounds ;  the  most  remarkable  of  which  are  those 
arising  from  its  union  with  oxygen   and    hydrogen.      It  forms 
several  oxides  and  acids,  and  one  of  the  latter,  sulphuric  acid, 
oil  of  vitriol  of  commerce,  is  much  used  both  alone  and  in  combi- 
nation, for  medical  and  technical  purposes.    With  hydrogen,  sul- 
phur forms  a  peculiar  gas,  which  has  some  of  the  properties  of  an 
acid ;  and  which  is  given  off  during  the  putrefaction  of  animal 
substances,  causing  a  peculiar  offensive  smell,  resembling  that  of 
rotten  eggs  ;  it  was  formerly  called  hepatic  air. 

42.  PHOSPHORUS,  like  sulphur,  is  a  solid   but  readily  volatile 
substance ;    but  is  never  found  in  nature  in  an  uncombined  state. 

What  are  some  of  its  compounds  with  oxygen  ? 

What  are  some  of  the  properties  of  silicon  ? 

What  are  the  distinguishing  characters  of  boron? 

In  what  connexion  with  other  substances  is  it  usually  seen  in  commerce  ? 

How  does  sulphur  exist  in  nature  ? 

What  are  its  most  usual  forms  when  prepared  for  the  arts  ? 

With  what  bodies  does  it  Ibrm  the  most  important  of  its  compounds? 

By  what  name  was  sulphuretted  hydrogen  formerly  known  ? 

In  what  condition  is  phosphorus  found  in  nature? 


FLUORINE.  .     23 

Some  of  its  compounds  occur  occasionally  in  mineral  substances  , 
but  it  is  most  abundantly  contained  in  certain  animal  fluids  and 
solids,  and  especially  in  bone,  from  which  it  is  usually  obtained 
for  experimental  purposes.  Phosphorus  is  found  in  the  shops  in 
the  form  of  small  cylinders,-semi-transparent,  and  nearly  of  the 
consistence  of  wax,  internally  of  a  reddish  or  flesh  colour,  but 
coated  with  a  white  film,  arising  from  its  partial  decomposition. 
It  so  strongly  attracts  oxygen  from  the  air  as  to  become  slowly 
decomposed  at  a  very  low  temperature,  and  hence  it  is  usually 
kept  under  water. .  With  oxygen  it  forms  two  acids,  one  of  which, 
the  phosphoric  acid, In  combination  with  lime  or  calcareous  earth, 
constitutes  the  basis  of  bone./  It  unites  with  hydrogen,  to  form 
an  inflammable  gas  ;""•  and  it  also  enters  into  combination  with 
various  other  bodies. 

43.  IODINE  is  a  bluish-black  or  violet-coloured  solid,  having  a 
metallic  lustre.     It  is  contained  in  sea-water,  and  in  some  marine 
productions,  as  seaweed    and  sponge ;    and  it  is  supposed  that 
burnt  sponge,  which  is  used  in  medicine,  owes  its  vi'rtues  to  the 
presence  of  iodine.     This  body,  like  oxygen  and  chlorine,  is  not 
itself  combustible,  but  is  a  supporter  of  combustion.  It  unites  with 
various  other  simple  substances ;    and  with  oxygen  and  chlorine,; 
it  forms  respectively  acid  compounds. 

44.  BROMINE,  like  iodine,  is  a  marine  production,  and  it  is 
usually  procured  from  the  refuse  liquor  obtained  in  making  sea 
salt.     Its  common  form  is  that  of  a  cloudy  red  liquid,  having  a 
very  disagreeable  smell  and  tase.     It  is  one  of  the  supporters  of 
combustion,  and  enters   into  union  with  various  simple  bodies, 
forming  acids  both  with  oxygen  and  chlorine.     In  many  respects, 
it  bears  a  strong  analogy  to  iodine,  and  has  been  supposed  to  be 
a  compound  of  that  body  with  chlorine  ;    but  there  appears  to  be 
sufficient  evidence  of  its  elementary  nature. 

45.  FLUORINE  is  generally  regarded  as  an  elementary  body, 
though  it  has  never  yet  been  exhibited  in  a  separate  state,  in  con- 
sequence of  its  powerful  tendency  to  form  combinations  with  all 
known  substances.'    Some  of  its  compounds  enter  into  the  com- 
position of  certain  minerals,  among  which  the  best  known  is  that 
called   fluor    spar,  found    in  Derbyshire ;     and  which,  from  its 
beauty  and  the  facility  with  which  it  may  be  cut  and  polished,  is 
frequently  used  for    making  chimney  ornaments   and   for  other 
purposes.      Among  the  artificial  compounds  of  fluorine,  one  of 

From  what  source  is  it  usually  obtained  ? 

In  what  form  and  consistence  is  it  commonly  found  in  commerce  ? 

What  are  its  important  sensible  properties  ? 

Why  is  it  usually  kept  under  water  ? 

With  what  other  ingredients  is  it  combined  in  the  bones  of  animals  ? 

What  is  the  colour  of  iodine  ? 

How  is  this  substance  related  to  the  process  of  combustion  ? 

With  what4substances  does  it  unite  to  form  acids  ? 

Why  cannot  fluorine  be  exhibited  in  a  separate  state  ? 

In  what  natural  bodies  is  it  found  ? 


24  CHEMISTRY. 

the  most  important  is  that  which  it  forms  with  hydrogen,  called 
hydro-fluoric  acid,  which  has  the  property  of  corroding  glass. 

46.  SELENIUM  is  a  reddish-gray  solid,  obtained  from  pyrites, 
and  in  many  of  its  properties  resembling  sulphur,  being  like  that 
body  readily  combustible.     It  has  hitherto  been  found  only  in  a 
few  places,  and  in  small  quantities.     It  forms  acids  in  combina- 
tion with  oxygen  ;  and  it  also  unites  with  hydrogen  and  chlorine, 
and  probably  with  other  elementary  substances. 

47.  METALS. — The  metallic  elements,  as  already  observed,  dis- 
play great  diversity  as  to  their  general  appearance  and  properties  ; 
and  there  is,  on  the  other  hand,  so  much  similarity  between  some 
of  these  bodies  and  some  of  the  non-meta'llic  elements,  that  their 
distinction  becomes  difficult  and  inconsiderable.      Hence  some 
chemists  have  hesitated  as  to  the  proper  mode  of  classifying  cer- 
tain substances.       Silicon  and  selenium  have  both  been  regarded 
as  metals ;  and  among  the  bodies  which  have  been  always  admit- 
ted into  the  first  class,  there  is  not  any  perhaps  which  so  much 
resembles  the  metals  as  carbon,  in  that  state  of  aggregation  which 
constitutes  charcoal. 

48.  The  elementary  or  simple  substances,  metallic  and  non- 
metallic,  have  so  many  points  of  analogy  as  to  render  it  impossi- 
ble to  form  a  systematic  arrangement  of  them,  adapted  for  practical 
purposes,  which  may  not  be  liable  to  objection.      In  this  as  well 
as  in  other  cases,  nature  seems  to  display  a  variety  of  bodies  not 
capable  of  being  separated  into  orders  or  sections,  strikingly  con- 
trasted with  each  other,  but  throughout  the  whole  a  gradation  ap- 
pears to  take  place ;   whence  may  be  deduced  a  chain  of  simple 
bodies,  variously  connected  with  each  other :    those  that  in  some 
respects  obviously  appear  to   be  members  of  different  classes, 
approaching  nearly  together  in  certain  of  their  properties  and 
modes  of  action.     However,  the  usual  arrangement  of  the  simple 
bodies  into  metals,  and  those  which  are  not  metals,  may  be  con- 
veniently retained,  as  affording  perhaps  the  most  generally  appli- 
cable method  of  distinguishing  them. 

49.  It  will  be  unnecessary  to  notice  separately  each   of  the 
metallic  elements,  as  we  have  done  those  of  a  non-metallic  nature ; 
because  several  of  them  are,  as  to  their  general  properties,  familiar- 
ly known,  being  used  either  in  a  state  of  purity,  or  combined  one 
with  another  (forming  simple  or  compound  metals),  for  many 
common  purposes.      Thus  iron  is  the  usual  material  for  the  con- 
struction of  a  vast   multitude   of  instruments   and  utensils  for 

What  compound  have  chemists  prepared  from  fluorine  and  what  is  its 
use  ? 

What  are  the  properties  of  selenium  ? 

From  what  substances  is  it  obtained  ? 

Which  of  the  bodies  already  described  have  been  sometimes  regarded 
as  metals  ? 

What  appears  to  be  the  probability  of  arriving  at  a  perfect  classification 
of  bodies  on  the  basis  of  distinct  peculiarities? 

What  circumstance  renders  a  minute  description  of  the  properties  ot 
metals  unnecessary  ? 


METALS.  25 

Domestic  and  other  purposes;  gold,  silver,  and  copper,  have 
been  long  employed  in  making  the  coin  current  in  all  civilized 
countries;  lead  is  used  in  sheets  for  covering  the  roofs  of  build- 
ings, in  tubes  for  making  waterpipes,  and  on  many  other  occa- 
sions; mercury  is  well  known  as  remaining  fluid  at  a  lower 
temperature  than  any  other  metal,  or  indeed  than  almost  any  other 
liquid  :  and  it  is  therefore  used  in  the  construction  of  thermome- 
ters and  other  philosophical  instruments.  Zinc  is  often  used  in 
combination  with  other  metals,  as  with  copper  in  the  manufacture 
of  brass,  and  it  is  likewise  employed  alone,  instead  of  lead,  for 
covering  houses ;  and  tin  is  not  only  of  general  utility  for  coat- 
ing other  metals,  as  in  making  tin  plate,  but  also  in  its  combina- 
tion with  copper  forming  bronze  or  bell-metal. 

50.  Perhaps  the  metals  may  be  most  properly  characterized 
with  reference  to  their  power  as  conductors  of  electricity,  which 
belongs  to  all  of  them  in  a  high  degree.      This,  however,  is  not 
an    exclusive   character   of    the  metallic   elements,    for   carbon 
(charcoal)  is  also  a  good  conductor  of  electricity,  and  in  this 
respect  it  more  nearly  corresponds  with  the  metals  than  silicon 
or  selenium,  which    are  non-conductors.      Among  the  acknow- 
ledged metals  there  are  many  which  differ  greatly  from  the  more 
common  metallic  bodies,  in  being  neither  malleable  nor  ductile : 
such  are  antimony,  arsenic,  cobalt,  and  manganese.     There  are 
others  which  are  distinguished  by  having  a  very  strong  affinity 
for  oxygen ;   so  that  at  low  temperatures  they  decompose  atmos- 
pheric air  or  water,  uniting  with  the  oxygen  in  those  bodies  to 
form  metallic  oxides ;   as  is  found  to  be  the  case  with  the  metals 
•which  Sir  H.  Davy  discovered  to  be  the  bases  of  potash  and  soda. 
Therefore  when  these  metals,  named  potassium  and  sodium,  are 
obtained  from  the  decomposition  of  their  respective  oxides,  potash 
and  soda,  the  metals  thus  formed  can  only  be  preserved  by  keep- 
ing them  immersed  in  ether,  which  does  not  act  on  them. 

51.  Hence  it  appears  that  those  bodies  formerly  termed  fixed  al- 
kalies are  metallic  oxides :  and  this  is  also  the  case  with  the  differ- 
ent earths  ;  thus  calcium  is  a  metal  which  combined  with  oxygen 
forms  calcareous   earth   or   lime,    a   substance   which    abounds 
especially  in  the  animal  and  mineral  kingdoms  of  nature.     The 
earth  called  barytes  is  an  oxide  of  the  metal  baryum;  strontites 
is  an  oxide  of  the  metal  strontium ;  magnesia,  in  its  pure  state, 
commonly  called  calcined  magnesia,    is  an  oxide  of  the  metal 
magnesium  ;  and  alumine,  argillaceous  earth  or  pure  clay,  is  an 
oxide  of  the  metal  aluminum.     The  more  rare  kinds  of  earths, 

In  what  manner  is  zinc  extensively  employed  ? 

In  what  different  ways  is  tin  applied  to  other  metals  ? 

According  to  what  characteristic  property  have  the  metals  been  classed 
by  Sir  H.  Davy. 

For  what  remarkable  property  are  potassium  and  sodium  distinguished  ? 

What  is  the  true  nature  of  the  bodies  formerly  called  fixed  alkalies  and 
earths  ? 

In  what  respect  does  silicon  differ  from  the  other  earths  ? 


26  CHEMISTRY. 

called  yttria,  glucina,  zircon,  and  thorina,  are  also  metallic 
oxides ;  and  it  has  been  already  stated  that  silica,  pure  siliceous 
earth,  is  an  oxide,  though  its  basis,  silicon,  is  not  a  metallic 
body. 

Chemical  Affinity. 

52.  That  property  of  matter  which  occasions  the  combination  of 
heterogeneous  bodies,  is  the  cause  of  the  principal  phenomena  of 
chemistry,  and  is  therefore  called  Chemical  Affinity  or  Attraction. 
It  is  also  sometimes  termed  Elective  Attraction,  and  the  Attraction 
of  Composition,  to  distinguish  it  from  Cohesive  Aggregative  At- 
traction.   This  interesting  subject  was  first  systematically  studied 
in  France  by  M.  Geoffroy,  who  formed  a  table  of  elective  attrac- 
tions.    Bergmann  in  Sweden,  Kirwan  in  England,  Berthollet  in 
France,   and   Richter  in    Germany,    afterwards   paid    particular 
attention  to  this  branch   of  science ;  and  the  subsequent  labours 
of  Dalton,  and  Sir  H.  Davy,  and  of  the  illustrious  Berzelius,  Gay 
Lussac,  Thenard  and  others,  have  made  vast  additions  to  our 
knowledge,   concerning   this   fundamental   branch   of   chemical 
science. 

53.  Chemical  Attraction  may  be  defined  to  be  that  energy,  in 
consequence  of  which,  different  kinds  of  matter  unite   to  form 
compounds  having  properties  often  dissimilar  from  those  of  their 
component  parts,  so  that  the  result  of  chemical  combination  can 
only  be  ascertained,  at  least  in  the  first  instance,  by  experiment. 
Thus,  if  iron  filings  be  dissolved  in   sulphuric  acid,  or  as  it  is 
commonly  called,  oil  of  vitriol,  a  substance  will  be  produced 
bearing  no  kind  of  resemblance  to  either  of  its  component  parts, 
called   by  chemists  sulphate  of  iron,  and  vulgarly  copperas,  or 
green  vitriol,  which  is  a  greenish,  semi-transparent,  crystallized 
substance,  having  nothing  of  the  appearance  -of  the  metal,  nor 
of  the  sour  taste   of  the  acid.     Acetic   acid,    or   the   acid    of 
vinegar,  in  the  same  manner  dissolves  copper,  and  constitutes 
with  it  the  blue  efflorescent  salt  called  verdigris.    Caustic  vege- 
table  alkali  is  a  deliquescent  substance,  which,  as  its  name  im- 
plies, corrodes  flesh  ;  and  sulphuric  acid,  already  mentioned,  is 
a  liquid  which,  when  concentrated,  acts  much  in  the  same  man- 
ner on  flesh,  but  from  the  union  of  these  bodies,  so  destructive  to 
animal  matter,  results  the  chemical  compound, ..sulphate  of  pot- 
ash, a  salt  which,  whether  solid  or  dissolved  in  water,  does  not 
act  on  the  skin,  and  may  be  swallowed  with  safety,  being  used 

What  causes  the  principal  phenomena  of  chemistry  ? 

By  whom  has  the  subject  of  chemical  attraction  been  extensively  culti- 
vated ? 

In  what  manner  may  its  results  be  ascertained  ? 

What  effect  on  the  sensible  properties  of  the  ingredients  is  often  pro- 
duced by  chemical  composition? 

What  examples  illustrate  this  point  ? 

How  does  sulphuric  acid  affect  the  skin  ? 

What  effect  does  caustic  potash  produce  upon  it? 

What  is  the  operation  of  sulphate  of  potash  on  the  living  flesh? 


CHEMICAL  AFFINITY.  27 

like  the  somewhat  similar  compound,  sulphate  of  soda,  (Glauber 
salt,)  for  medicinal  purposes.  Sometimes  two  liquids,  or  gaseous 
bodies,  by  their  union,  form  a  solid  compound.  Thus  the  gas 
that  rises  from  spirit  of  hartshorn,  called  by  chemists  ammonia, 
and  muriatic  acid  gas,  if  mixed  together  in  an  empty  jar,  become 
condensed  into  a  white  saline  solid,  called  muriate  of  ammonia, 
or  sal-ammoniac. 


54.  The  manner  in  which  the  effect  just  mentioned  maybe  conve- 
niently exhibited,   is  presented  in  the  above  figure,  where  two 
retorts,  S  and  L,  are  connected  with  a  glass  globe,  by  means 
of  two   tubulures,   into   which    their    necks    respectively    pass 
until    they   nearly   meet  in    the   centre.     The   apparatus   being 
thus  prepared,  we  put  into  L  a  mixture  of  dry  slaked  lime  and 
sal-ammoniac  in  fine  powder.     Into  the  retort  S  put  a  quantity  of 
common  salt,  sufficient  to  fill  one-third  of  the  bulb.     Place  the 
globe  on  its  support,  apply  a  moderate  heat  to  L,  and  pour  sul- 
phuric  acid   upon   the  salt  in  S.     Close  both  retorts,  and  the 
gaseous  ammonia  from  L  will  combine  with  the  muriatic  acid 
gas  from  S,  forming  in  the  globe  a  dense  white  cloud  or  solid 
substance,  the  muriate  of  ammonia. 

55.  The  phenomena  of  Chemical  Attraction  are  regulated  by 
the  following  laws : 

(1.)  This  attractive  force  is  exerted  in  different  degrees  by 
different  bodies. 

(2.)  It  operates  only  on  very  minute  particles  of  bodies;  and 
hence  chemical  action  is  promoted  by  previous  solution,  trituration, 
or  other  mechanical  methods  of  division  and  intermixture. 

(3.)  When  bodies  combine,  an  alteration  of  temperature  gener- 
ally takes  place,  sometimes  with  the  exhibition  of  light. 

(4.)  Bodies  which  have  an  attraction  for  each  other,  are  always 
found  to  display  opposite  states  of  electricity. 

What  is  the  first  law  of  chemical  attraction  ? 

What  is  the  effect  of  mechanical  division  on  the  chemical  combination 
of  bodies  1 

What  sensible  phenomena  usually  accompany  chemical  changes  ? 

In  what  relative  electrical  states  are  two  combining  bodies  always  found? 


28  CHEMISTRY. 

(5.)  All  bodies  are  composed  of  certain  atoms  or  molecules,  and 
chemical  combination  consists  of  the  union  of  one  or  more  atoms 
of  one  of  the  uniting  bodies,  with  some  determinate  number  of 
atoms  of  the  other  uniting-  body. 

(6.)  Chemical  attraction  takes  place  in  three  different  modes  : — 
[1.]  When  one  simple  body  is  presented  to  another,  for  which  it 
has  an  affinity,  a  union  takes  place,  and  a  compound  is  formed. 
[2.]  If  a  simple  body,  A,  be  presented  to  a  compound,  B  C, 
and  if  A  have  a  stronger  affinity  for  B  than  C  has,  the  compound 
B  C  will  be  decomposed,  and  a  new  compound,  A  B,  will  be 
formed.  [3.]  If  a  compound  A  B,  be  presented  to  another  com- 
pound C  D,  though  neither  A  nor  B  alone  would  decompose  C  D, 
yet  a  mutual  decomposition  may  take  place  between  the  two 
compounds,  and  occasion  the  formation  of  two  new  compounds, 
A  D  and  C  B.  The  first  and  second  modes*  of  attraction  are 
styled  instances  of  simple  affinity,  or  simple  elective  attraction; 
and  the  last  mode  is  styled  compound  affinity,  or  compound  elec- 
tive attraction. 

(7.)  All  compounds,  when  they  enter  into  union  with  other  bo- 
dies without  being  decomposed,  act  in  the  same  manner  as  simple 
bodies. 

56.  These  laws  of  Chemical  Attraction  may  be  exemplified 
and  illustrated  in  the  following  manner : 

(1.)  The  first  of  these  laws  constitutes  the  foundation  of  the 
whole  science  of  Chemistry.  The  ensuing  examples  show  the 
manner  in  which  it  operates. 

If  thin  plates  or  filings  of  copper  be  mixed  with  sulphuric 
acid,  (oil  of  vitroil,)  on  the  application  of  heat  the  metal  will  be 
dissolved.  The  acid  thus  united  to  the  copper  will  form  a  salt, 
called  sulphate  of  copper,  (blue  vitriol,)  which  might  be  ob- 
tained from  the  solution  by  evaporation  and  crystallization.  If 
to  this  solution  be  added  iron  wire,  or  thin  plates  of  that  metal, 
the  sulphuric  acid  will  leave  the  copper,  and  combine  with  the 
iron.  As  the  latter  dissolves,  the  former,  separating  from  its 
union  with  the  acid,  deposits  itself  on  the  iron  plates,  so  that  they 
become  covered  with  a  thin  film  of  copper,  but  when  the  iron  is 
all  dissolved,  the  copper  having  nothing  to  support  it,  will  fall  to 
the  bottom  of  the  containing  vessel,  in  a  pulverulent  form.  The 
clear  liquor,  being  decanted,  will  therefore  be  a  solution  of  sul- 
phate of  iron  (green  vitriol.)  If  to  this  solution  filings  or  frag- 
ments of  zinc  be  added,  the  iron  will  separate  by  degrees  from 
the  liquid  and  fall  down,  as  the  copper  previously  did,  leaving 

What  law  appears  to  regulate  combination  in  regard  to  the  numbers  of 
ultimate  particles  ? 

In  how  many  and  what  different  modes  may  chemical  attraction  take 
place  ? 

In  what  manner  do  compounds  act  when  their  exercise  of  chemical  at- 
traction is  not  attended  by  their  own  decomposition  ? 

In  what  manner  is  the  first  law  of  chemical  attraction  illustrated  by 
copper  and  sulphuric  acid  ? 

What  is  the  resulting  compound  called  ? 


MINUTENESS  OF  THE  PARTICLES  OF  MATTER.  29 

the  zinc  in  solution,  forming'  with  the  acid,  sulphate  of  zinc, 
(white  vitriol.)  If  to  the  solution  of  sulphate  of  zinc,  be  added 
water  of  ammonia,  (pure  volatile  alkali,)  the  acid  will  quit  the  zinc 
to  unite  with  the  alkali,  the  metal  will  be  precipitated,  and  the  clear 
liquor  being  decanted,  will  be  a  solution  of  sulphate  of  ammo- 
nia. Add  to  this  liquor  quicklime,  which  substance  will  combine 
with  the  acid,  and  separate  it  from  the  ammonia,  but  the  new 
compound  of  sulphuric  acid  and  lime,  thus  formed,  will  not 
remain  in  solution,  but  will  be  precipitated,  or  fall  down,  in  the 
form  of  a  white  powder,  called  sulphate  of  lime,  (gypsum,)  while 
the  ammonia,  freed  from  the  acid,  remains  dissolved  in  the  water, 
from  which  it  may  be  expelled  by  heat,  in  the  form  of  a  gas. 
If  the  sulphate  of  lime  be  separated  from  the  solution  by  filtering-, 
and  thrown  into  water  containing  caustic  potash,  a  new  decom- 
position wrill  take  place,  the  sulphuric  acid  leaving  the  lime,  and 
uniting  with  the  potash.  The  sulphate  of  potash  (vitriolated 
tartar)  thus  formed,  will  remain  in  solution  while  the  pure  lime 
becomes  precipitated  in  the  state  of  a  white  powder,  and  the 
sulphate  of  potash  may  be  obtained,  in  a  crystalline  form  by  eva- 
porating the  clear  solution,  after  pouring  it  from  the  lime. 

57.  This  succession  of  decompositions  shows  that  iron  possesses 
a  stronger  attraction  for  sulphuric  acid  than  copper,  zinc  than  iron, 
ammonia  than  zinc,  lime  than  ammonia,  and  potash  than  lime. 
Numerous  experiments  of  a  similar  kind  might  be  adduced,  which 
would  equally  serve  to  show  the  relative  attractive  powers  of 
various  substances.     It  appears  from  the  preceding  experiments, 
that  the  decomposition  of  a  substance  dissolved  in  a  liquid,  is 
sometimes  accompanied  by  the  falling  down  of  the  newly  formed 
substance,  and  sometimes  by  that  of  the  body  separated  from  the 
original  compound.    \In  this  case  the  body  added  to  produce  the 
decomposition  is  calle3  the  precipitant \  and  the  substance  thrown 
down  the  precipitate;  the  process  itself  is  sometimes  termed  pre- 
cipitation. } 

58.  (2.)  The  extreme  minuteness  of  the  elementary  molecules  of 
bodies  from  the  union  of  which  chemical  compounds  are  formed, 
appears  from  the  entire  change  of  sensible  properties  resulting 
from  such  combinations.     For  as  already  stated,  the  human  eye, 
assisted  by  the  most  powerful  microscopes  which  have  ever  been 
constructed,  ^ften   cannot   detect  in  a  chemical   compound    the 
slightest  vestige  of  the  colour  of  either  of  its  component  parts  ; 

By  what  means  may  the  copper  be  fe produced  in  its  metallic  state  ? 

What  will  then  be  the  nature  of  the  liquid  obtained  ? 

In  what  manner  may  the  iron  in  this  solution  be  reproduced  ? 

What  may  next  be  employed  to  separate  the  zinc? 

How  may  ammonia  be  freed  from  sulphuric  acid  ? 

Will  this  like  the  metals  undergo  precipitation  ? 

How  may  the  separation  of  lime  from  the  same  acid  be  effected  ? 

What  general  truths  may  we  deduce  from  this  series  of  operations? 

What  term  is  applied  to  the  body  which  produces  precipitation? 

What  name  is  sriven  lo  the  substance  thrown  down  ? 


30  CHEMISTRY. 

but  when  substances  are  mechanically  mixed,  the  respective 
colours  of  the  ingredients  of  the  composition  may  sometimes  be 
traced,  as  when  variously-tinted  powders  are  triturated  together; 
or  if  the  mixture  is  more  complete,  as  when  two  liquids,  for  in- 
stance, ink  and  water,  are  shaken  together  in  a  phial,  though 
the  whole  mass  will  exhibit  a  uniform  appearance,  it  will  be 
merely  a  modification  of  colour,  arising  from  the  dilution  of  the 
ink  by  the  aqueous  fluid./ 

59.  Some  philosophers  have  ascribed  to  matter  the  property 
of  infinite  divisibility.     But  though  matter  may  be  conceived  to 
be  indefinitely  capable  of  being  divided,  and  though  it  may  even 
be  proved  by  geometrical  demonstration,  that  a  line  of  a  given 
length  may  be  made  to  undergo  unlimited  subdivision,  yet  there 
is  reason  to  believe  that  those  bodies  with  which  chemistry  is 
conversant,  are   formed  of  indivisible  atomsu     Matter,  then,  or 
rather   space,   is   metaphysically   and   mathematically,  but   not 
physically,  capable  of  being  infinitely  divided.] 

60.  It  is  possible  to  conceive  that  a  cubic  inch  may  be  separated 
into  10,000  smaller  cubes,  and  each  of  the  latter  into  as  many 
millions  of  millions  of  minuter  parts  of  a  similar  shape,  nor  can 
there  be  any  limit  to  such  subdivision,  which  must  be  as  exten- 
sive  as   the   power    of   enumeration.^  \The    mathematical    de- 
monstration of  the  infinite  divisibility  of  matter  is  founded  on, 
the  impossibility  of  conceiving  any   limits   to   absolute   space. ' 
Let  A  D  and  F  G,  in  the  marginal  figure,  be  two  lines  parallel 

C         A         T?   n   ^h  eacn  other,  and  perpendicular  to  the 

line B C; then from the points H' H'' H"' H"/j 

as  centres,  describe  so  many  arcs  of  circles, 


0  cutting  the  lines  F  G  and  A  D ;  and  since, 
the  line  A  D  may  be  imagined  to  be  as  ex- 
tensive as  space  itself,  it  is  impossible  to 
prescribe  bounds  to  the  number  of  points 
which  may  be  made  the  centres  of  circular 
arcs,  and  as  the  number  of  arcs  is  bound- 
less, so  will  be  the  number  of  parts  into 
which  they  will  divide  the  line  F  G ;  for 
the  arc,  how  immense  soever  might  be  the  length  of  its  radius, 
could  not  possibly  become  coincident  with  the  right  line  B  C. 

61.  These  observations  are  worthy  of  attention,  as  they  may 
serve  to  assist  us  in  forming  distinct  conceptions  concerning  the 
wonderful  minuteness  of  the  particles  of  matter,  considered  in  a 
physical  point  of  view.  Among  the  numerous  instances  that 

What  difference  in  sensible  properties  may  distinguish  a  chemical  com- 
pound from  a  mechanical  mixture  ? 

What  examples  may  be  given  of  these  two  effects  ? 

What  opinion  has  been  formerly  promulgated  in  regard  to  the  divisi- 
bility of  matter  ? 

What  difference  exists  between  the  mathematical  and  the  physical  di- 
visibility of  space  ? 

On  what  is  the  mathematical  divisibility  of  space  founded  ? 

Draw  and  explain  the  diagram  relating  to  this  subject  ? 


BULK  OR  WEIGHT  OF  ATOMS.  81 

might  be  produced  of  the  minute  division  of  material  bodies,  may 
be  mentioned  the  extreme  diffusion  of  colouring  particles  through 
a  transparent  fluid.  A  grain  of  carmine  rubbed  down  with  a  little 
water,  and  then  mixed  with  six  quarts  more,  will  give  the  whole 
liquid  a  pale  red  or  flesh  colour;  and  one  grain  of  blue  vitriol, 
(sulphate  of  copper,)  will  communicate  a  fine  azure  tint  to  five 
gallons  of  water.  V Boyle  says  that  a  pair  of  Spanish  gloves, 
which  had  been  scented  by  a  single  grain  of  musk,  retained  their 
odour  for  twenty-nine  years.  The  same  philosopher  placed  a 
piece  of  amber,  weighing  100  grains,  in  the  scale  of  a  balance, 
which  turned  with  a  small  fraction  of  a  grain,  and,  having  counter- 
poised it,  he  left  it  for  several  days,  at  the  end  of  which  time  it 
had  lost  no  perceptible  portion  of  its  weight,  though  it  had  been 
continually  giving  off  particles,  which  had  perfumed  the  sur- 
rounding air.*") 

62.  Malleable  and  ductile  metals  are  capable  of  being  reduced 
to  a  most  extraordinary  degree  of  tenuity.  vGold,  after  being  sub- 
mitted to  the  operations  bf  the  goldbeater,  is  formed  into  leaves 
3.3  inches  square,  each  weighing  rather  less  than  the  fifth  part  of 
a  grain,  and  being  but  the  282,000th  part  of  an  inch  in  thickness  ; 
and  a  particle  of  this  gold  leaf,  not  exceeding  the  500,000th  of  a 
grain,  will  be  distinctly  visible  to  the  naked  eye.f     Still  more 
comminuted,  doubtless,  are  the  particles  of  gold  left  in  the  abra- 
sion of  a  gold  pin  on  a  touchstone,  but  yet  perfectly  perceptible 
to  the  sight.     Bubbles  of  soap  and  water  consist  of  films  far 
more  attenuated  than  leaf  gold,  for  when  they  begin  to  reflect 
colours,  their  thickness  is  less  than  2,000,000ths  of  an  inch,  and 
that  must  be  much  beyond  the  diameter  of  the  atoms  of  water ;  for 
the  film  contains  soap  incorporated  with  the  water,  and  we  cannot 
even  conjecture  what  relation  the  dimensions  of  the  atoms  of  the 
fluid  may  bear  to  those  of  the  film  which  it  forms,  only  they  must 
be  far  inferior.     Besides,  both  soap  and  water  are  compounds,  so 
that  the  constituent  atoms  of  those  substances,  as  of  the  oxygen 
and  hydrogen  of  the  water,  must  be  yet  more  reduced,  till  they 
almost  surpass  the  power  of  imagination. 

63.  v The  vegetable  kingdom  presents  us  with  innumerable  in- 
stances, not  only  of  the  extraordinary  divisibility  of  matter,  but 
of  its  activity,  in  the  almost  incredibly  rapid  developement  of  cel- 
lular structure  in  certain  plants.    /J'hus  the  Bovista  giganteum  (a 
species  of  fungus,  has  been  known  to  acquire  the  size  of  a  gourd 

What  examples  can  be  adduced  of  extreme  divisibility  among  colouring 
materials  ? 

What  facts  demonstrate  the  minuteness  of  odoriferous  particles? 

How  may  metallic  substances  be  perceived  to  illustrate  the  minute  di- 
visibility of  matter  ?  Illustrate  the  extreme  divisibility  and  the  activity  of 
matter  in  the  vegetable  kingdom  ? 

*  De  Mira  Subtil.  Effluv.     Sigaud  de  la  Fond.  Elem.  de  Phys.,  t.  i.  pp. 
156  et  160. 
t  Leslie's  Elem.  of  Nat.  Philos.,  vol.  i.  p.  13. 


32  CHEMISTRY. 

in  one  nighty  Now  supposing,  with  Professor  Lindley,  that  the 
cellules  of  this  plant  are  not  less  than  ^^th  of  an  inch  in 
diameter,  a  plant  of  the  ahove  size  will  contain  no  less  than 
47,000,000,000  cellules ;  so  that,  supposing  it  to  have  grown  in. 
the  course  of  twelve  hours,  its  cellules  must  have  been  developed 
at  the  rate  of  nearly  4,000,000,000  per  hour,  or  of  more  than 
66,000,000  in  a  minute;  and  when  we  consider  that  every  one  of 
these  cellules  must  be  composed  of  innumerable  molecules,  each 
one  of  which  is  again  composed  of  others,  we  are  perfectly  over- 
whelmed with  the  minuteness  and  number  of  the  parts  employed 
in  this  single  production  of  nature.* 

64.  The  animal  world  affords  examples  of  the  incomprehensi- 
ble divisibility  of  matter  not  less  wonderful.     Mr.  Harmer,  by 
counting  the  number  of  ova  in  a  given  weight  of  the  spawn  of 
different  fishes,  found  that  a  single  flounder  contained  1,357,400  ; 
and  a  cod-fish  no  less  than  3,686,760  ova ;  all  of  which,  it  must 
be  remembered,  were  organized  bodies,,capable  of  developement, 
so  as  to  form  perfect  animals. f     But  the  infusory  animalcules 
display,  in  their  structure  and  functions,  the  most  transcendent 
attenuation  of  matter.  \The  Vibrio  itndula,  found  in  duckweed,  is 
computed  to  be  ten  thousand  million  times  smaller  than  a  hemp- 
seed.      Vibrio  lineola  occurs  in  vegetable  infusions,  every  drop 
containing  myriads  cf  those  oblong  points^  The  Monas  gelatlnosa, 
discovered  in  ditch-water,  appears  in  the  field  of  a  microscope  a 
mere  atom  endued  with  life,  millions  of  them  playing  like  the 
Bun-beams,  in  a  single  drop  of  liquid.:}: 

65.  That  all  bodies  are  composed  of  atoms  or  ultimate  indivi- 
sible particles,  may  be  inferred  from  the  observations  which  have 
been  made  on  the  height  of  the  atmosphere  above  the  surface  of 
the  earth.     Dr.  Wollaston  adduced  some  ingenious  arguments  in 
proof  of  the  limited  extent  of  the  aerial  medium  which  surrounds 
the  globe,  as  resulting  from  its  atomic  constitution. §     And  if  we 
admit  that  such  is  the  nature  of  the  air,  it  may  also  be  concluded 
that  bodies  of  greater  density  consist  in  the  same  manner  of  indi- 
visible molecules. 

66.  The   instances   already   mentioned    of  the  extraordinary 
minuteness  of  particles  of  matter  relate  to  bodies  which  are  mani- 
festly compounds,  and   the  magnitude  of  such  particles   must 
therefore  be  far  superior  to  that  of  the  ultimate  or  even  the  con- 
stituent molecules  of  those  bodies.     With  regard  to  the  bulk  or 


At  what  rote  per  second  are  the  cells  of  the  Bovista  giganteum  developed  ? 
What  is  supposed  to  be  the  size  of  the  Vibrio  undnLa  ? 

How  may  we  i    '     A !-*:~  -<•-—•  "— ' 

our  atmosphere  ? 


How  may  we  infer  the  atomic  constitution  of  mattet,  from  the  nature  of 
)h 


r.  Prout's  Chemistry,  Meteorology,  and  the  Function  of  Digestion 
Bred  with  reference  to  Natural  Theology,  1834,  pp.  23,  24 ;    from 


*  Dr. 

considered 

Lindley's  introduction  to  Botany. 

t  Philosoph.  Transact.,  vol.  Ivii.  1767,  art.  30. 

t  Leslie's  Nat.  Philos.,  vol.  i.  p.  16. 

$  Sec  Scientific  class  Book,  part  i.  p.  207. 


COMBUSTION.  3* 

weight  of  absolute  atoms,  or  ultimate  molecules  of  matter,  we  can 
form  no  conceptions  whatever,  and  their  nature  and  properties 
must  probably  remain  objects  of  conjecture  and  uncertainty;  but 
the  constituent  or  combining  molecules  of  different  substances  are 
more  within  the  reach  of  experiment  and  observation,  and  con- 
cerning their  relative  magnitudes  or  proportional  weights,  the  re- 
searches of  modern  philosophers  furnish  us  with  some  infor- 
mation. Dr.  Thompson  has  calculated  that  the  weight  of  a 
constituent  molecule  of  lead  does  not  exceed  3-To",o"o~olwo\5"o^th. 
of  a  grain,  and  that  its  magnitude  is  probably  much  less  than 

T5"8,4F2,-<5-W,o-o <5-,o-o-otri  of  a  cubic  inch-  The  combining  mole- 
cules of  sulphur  are  vastly  inferior  to  those  of  lead,  each  being 

computed  to  be  not  more  than  T^j/oiTo.o-o-o.o-o^h  of  a  grain  5 
and  the  molecules  of  some  other  bodies  are  undoubtedly  much 
more  diminutive.* 

67.  The  change  of  temperature  that  results  from  chemical  com- 
bination is  sometimes  very  considerable.  Thus  the  burning  of  char- 
coal is  a  combination  of  charcoal  or  carbon  with  the  oxygen  of  the 
atmosphere,  and  the  consequent  production  of  carbonic  acid.  Abun- 
dance of  heat  is  evolved  in  this  process,  which  has  been  supposed 
to  be  derived  from  the  oxygen  gas  consumed.    Much  heat  is  also 
given  out  when  nitrous  acid  or  aqua  fortis  is  mixed  with  oil  of 
amber ;  those  fluids  uniting  to  form  a  resinous  substance,  which, 
from  its  peculiar  odour,  has  obtained  the  name  of  artificial  musk. 

68.  The  elevation  or  depression  of  temperature  which  accompa- 
nies the  formation  of  chemical  compounds  has  given  rise  to  various 
hypotheses,  among  which  the  most  plausible,  perhaps,  is  that  which 
deduces  the  heat  or  cold  manifested  in  such  cases  from  the  change 
of  state  in  the  elements  of  the  combining  bodies,  or  the  relation 
of  their  respective  capacities  for  heat  with  that  of  the  compound. 
Thus  it  has  been  imagined,  that  when  the  specific  heat  of  a 
compound  is  less  than  that  of  the  bodies  from  whose  union  it  is 
formed,  the  superabundant  heat  will  be  given  out  and  become 
sensible;  and  if  the  specific  heat  of  the  compound  be  greater 
than  that  of  its  component  parts,  it  must  absorb  heat  from  sur- 
rounding bodies,  and  thus  occasion  a  sensible  depression  of  tem- 
perature.   But  this  view  of  the  cause  of  the  changes  of  temperature 
that  take  place,  is  hardly  consistent  with  the  conclusions  derived 

What  is  the  state  of  our  knowledge  in  regard  to  the  ultimate  particles 
of  simple  bodies? 

What  has  modern  chemistry  developed  in  regard  to  the  relative  weights 
of  the  combining  atoms  of  different  substances  ? 

How  does  the  size  of  a  combining  atom  of  sulphur  compare  with  one  of 
lead  ? 

What  remarkable  examples  illustrate  the  third  law  of  chemical  attrac- 
tion? 

What  hypotheses  have  been  raised  to  account  for  the  developement  of 
heat  during  chemical  combination  ? 

*  Thomsons's  Principles  of  Inorganic  chemistry,  vol.  i.  p.  7. 


34  CHEMISTRY. 

from  the  latest  researches  of  philosophers  concerning-  the  specific 
heat  of  different  bodies,  and  especially  of  gases  ;  and  the  relation 
of  chemical  attraction  to  heat  is  a  subject  which  still  remains 
open  for  future  investigation. 

G9.  A  few  observations  may,  however,  be  added  concerning 
two  important  topics  connected  with  this  law  of  chemical  affinity, 
namely,  Combustion,  and  the  Solution  of  Solids  in  Liquids. 

The  term  combustion  has  been  variously  applied  by  different 
writers  ;  some  extending  it  to  all  cases  of  violent  chemical  action, 
accompanied  by  the  evolution  of  light  and  heat ;  and  others  re- 
stricting it  to  certain  processes  in  which  combustible  bodies  more 
or  less  rapidly  combine  with  oxygen,  with  the  extrication  of  light 
and  heat,  as  in  the  burning  of  charcoal,  noticed  above..  .Lavoisier,  < 
who  was  the  first  in  modern  times  that  clearly  ascertained  the 
influence  of  atmospheric  air  on  chemical  operations,  and  showed 
that  the  changes  which  bodies  undergo  frequently  depend  on  the 
absorption  of  oxygen,  ;was  led  to  conclude  that  all  simple  sub- 
stances might  be  arranged  in  two  classes ;  the  first  comprising 
oxygen  only,  which  he  characterised  as  a  supporter  of  combustion  ; 
and  the  second,  consisting  of  combustible  bodies,  including  the 
metals.  Hence  he  farther  inferred  that  oxygen  gas  consisted  of 
a  ponderable  basis,  combined  with  light  and  heat,  which  were 
given  out  in  the  form  of  flame  during  combustion  or  the  union  of 
combustible  bodies,  as  carbon,  sulphur,  phosphorus,  oil,  and  alco- 
hol, with  the  basis  of  oxygen  gas. ) 

70.  But  this  theory,  though  to  a  certain  extent  it  may  be 
admitted,  is  by  no  means  applicable  to  all  cases  of  combustion 
in  which  oxygen  gas  or  atmospheric  air  is  present,  and  it  is 
necessarily  incapable  of  affording  an  explanation  of  those  in- 
stances of  the  evolution  of  light  and  heat  consequent  on  the  sud- 
den union  of  bodies  which  contain  no  oxygen  whatever.  ^  Thus 
if  equal  volumes  of  chlorine  gas  and  hydrogen  gas  be  introduced 
into  a  glass  jar,  and  exposed  to  the  direct  rays  of  the  sun,  they 
rapidly  combine,  with  explosion,  or  the  display  of  abundance  of 
light  and  heat.    Phosphorus  burns  with  a  pale  yellow  flame,  when 
heated  in  chlorine  gas;  and  when  phosphorus  is  introduced  into 
an  exhausted  vessel  with  iodine,  a  violent  action  takes  place,  and 
much  heat  is  extricated,  but  without  light.    If  sulphur  and  filings 
of  copper  be  heated  together,  when  the  mixture  has  acquired  a 
temperature  much  below  a  red  heat,  it  suddenly  becomes  red-hot, 
and  the  compound  called  sulphuret  of  copper  is  formed.  ) 

71.  Many  other  examples  might  be  adduced  of  the  production 

What  researches  of  morlern  times  are  found  to  oppose  this  theory  ? 

How  has  the  term  combustion  been  used  by  different  writers? 

By  whom  was  the  distinction  of  bodies  into  combustibles  and  supporters 
of  combustion  first  made  ? 

What  led  the  author  to  this  division  ? 

How  has  the  theory  of  Lavoisier  been  modified  by  more  recent  disco- 
veries ? 

Give  some  examples  of  the  phenomena  of  combustion  produced  with- 
out the  presence  of  oxygen. 


SPONTANEOUS  COMBUSTION.  35 

of  heat  either  alone  or  accompanied  by  light,  during  chemical 
combinations,  in  which  oxygen  is  not  at  all  concerned.  Unless, 
therefore,  the  term  Combustion  be  exclusively  appropriated  to  the 
process  of  burning  combustibles  in  atmospheric  air,  or  some  other 
aerial  medium  in  which  oxygen  is  contained,  the  phenomena  with 
which  the  process  is  accompanied  cannot  possibly  be  said  to  be 
caused  by  the  condensation  of  oxygen  gas ;  and  in  the  present 
state  of  our  knowledge,  any  attempt  to  develope  their  source  may 
be  considered  as  somewhat  premature. 

72.\^Combustion,  as  depending  on  the  union  of  oxygen  with  a 
combustible  body,  sometimes  takes  place  under  singular  circum- 
stances, and  gives  rise  to  extraordinary  appearances.  The  tem- 
peratures at  which  different  combustibles  combine  with  oxygen 
vary  extremely.;  Potassium,  or  the  metallic  body  which  in  com- 
bination with  oxygen  forms  potash  or  fixed  vegetable  alkali,  most 
powerfully  attracts  oxygen,  tarnishing  when  exposed  to  the  air  at  a 
very  low  temperature,  and  becoming  inflamed  when  thrown  into 
cold  water,  or  even  when  placed  on  a  piece  of  ice,  potash  being 
formed  in  either  case.  Phosphorus,  when  quite  dry,  takes  fire  in  at- 
mospheric air,  at  about  100°  of  Fahrenheit.  Sulphur  burns  in  com- 
mon air  at  from  180°  to  190°,  but  with  a  faint  blue  flame,  the  heat 
of  which  is  very  inconsiderable;  but  if  its  temperature  be  raised 
to  300°,  the  combustion  proceeds  more  rapidly.  -.Carbon,  in  the 
state  of  common  charcoal,  demands  a  higher  temperature  for  its 
combustion  than  the  substances  already  mentioned ;  and  in  its 
crystallized  form,  in  the  diamond,  it  requires  an  intense  heat,  as 
the  flame  of  an  oxy-hydrogen  blowpipe,  to  set  it  on  fire.  When 
highly  comminuted,  however,  charcoal,  and  especially  some 
varieties  of  it,  attract  oxygen,  exhibiting  the  phenomena  of  com- 
bustion at  relatively  low  temperatures  ;  and  hence,  in  certain 
cases,  what  is  termed  spontaneous  inflammation  has  taken  place. 

73.  Colonel  Aubert,  an  artillery  officer,  in  consequence  of  re- 
peated instances  of  the  spontaneous  combustion  of  powdered 
charcoal  which  had  occurred  in  France,  made  some  interesting 
experiments  on  the  subject.  He  found  that  charcoal  triturated  in 
mortars  with  bronze  pestles,  till  it  is  reduced  to  the  finest  powder, 
has  the  appearance  of  an  oily  fluid,  and  occupies  only  one-third 
of  the  space  which  it  takes  up  when  in  the  form  of  rods  about  six 
inches  in  length.  In  this  state  of  extreme  division  it  absorbs  air 
much  more  readily  than  before ;  but  the  absorption  proceeds 
slowly,  requiring  several  days  for  its  completion,  and  it  is  accom- 
panied by  the  evolution  of  heat  sufficient  to  raise  the  thermometer 
to  about  360°  of  Fahrenheit,  and  thus  inflammation  is  occasioned. 
The  process  commences  near  the  centre  of  the  mass,  about  five  or 
six  inches  from  its  surface,  at  which  spot  the  temperature  is 

Under  what  variety  of  circumstances  may  combustion  take  place  ? 
What  remarkable  instance  may  be  adduced  in  which  combustion  com- 
mences  at  low  temperatures  ? 

Under  what  different  circumstances  may  carbon  be  ignited  ? 

What  investigation  was  made  by  Aubert  on  the  combustion  of  charcoal  ? 


36  CHEMISTRY. 

always  higher  than  at  any  other.  Black  charcoal,  strongly  dis- 
tilled, is  more  readily  inflammable  than  lighter  varieties.  Masses 
of  this  kind  of  charcoal,  less  than  66  pounds  avoirdupois,  do  not 
inflame  spontaneously ;  and  the  other  kinds  inflame  only  when  in 
larger  masses.  The  free  admission  of  air  to  the  surface  is  indis- 
pensably requisite  to  produce  spontaneous  combustion.  When 
sulphur  and  nitre  are  added  to  the  pulverized  charcoal,  the  in- 
flammation does  not  take  place  as  usual ;  but  there  is  still  some 
absorption  of  air,  and  augmentation  of  temperature ;  therefore  it 
would  be  dangerous  to  leave  large  quantities  of  such  mixtures 
long  exposed  to  the  air.* 

74.  The  spontaneous  combustion  of  substances  containing  car- 
bon, from  the  absorption  of  air  and  moisture  is  a  phenomenon 
of  so  frequent  occurrence  that  few  persons  can  be  ignorant  of  it, 
though  those  who  are  unacquainted  with  chemistry  must  be  at  a 
loss  to  account  for  it.     Ricks  of  hay  arid  stacks  of  corn  thus  oc- 
casionally take  fire,  and  are  consumed ;    and  repeated  narratives 
have  been  published  of  the  destruction  of  packages  of  coffee, 
bales  of  cotton  and  other  articles,  in  consequence  of  spontaneous 
inflammation.     Much  appears  to  depend  in  these  cases  on  the  pre- 
sence of  water;  for  hay-ricks  take  fire  only  when  the  hay  is  put 
together  before  it  is  properly  dried,  or  in  consequence  of  its  not 
being  well  secured  from  the  rain.    An  instance  of  the  spontaneous 
combustion  of  a  quantity  of  oatmeal,  which  had  been  left  in  the 
house  of  a  gentleman  at  Glasgow,  during  the  absence  of  his  fa- 
mily from  home  from  May  till  the  end  of  August,  in    1820,  is 
mentioned  in  Dr.  Thomson's  "Annals  of  Philosophy;"  and  the 
accident  is  justly  attributed  to  the  avidity  with  which  oatmeal 
attracts   moisture,  a  property  that  induced  Professor  Leslie  to 
employ  it  instead  of  sulphuric  acid,  in  his  ingenious  process  for  the 
production  of  ice  under  the  exhausted  receiver  of  an  airpump.f 

75.  Spontaneous  combustion  sometimes  takes  place  very  sud- 
denly.    Prof.  Bache,  of  Philadelphia,  discovered  that  carbon  in 
the  state  of  lamp-black,  or  the  soot  of  animal  oil,  causes  the  in- 
flammation of  a  stick  of  phosphorus  powdered  with  it,  at  the  tem- 
perature of  60°  of  Fahrenheit,  either  in  the  open  air,  or  in  a  close 
receiver  of  a  moderate  size.}: 

76.  Professor  Doberiener,  of  Jena,  discovered  a  curious  phe- 
nomenon of  an  analogous  nature  relative*4o  spontaneous  combus- 
tion in  1823.     He  found  that  platina,  in  the  state  of  very  fine 
wire,  thin  leaves,  powder,  or  in  the  spongy  form,  at  the  common 
temperature  of  the  air,  if  plunged  into  a  mixture  of  hydrogen  gas 

What  effect  on  the  combustibility  of  powdered  charcoal  arises  from 
mixing  with  it  sulphur  and  nitre  ?  How  may  the  spontaneous  combustion 
of  hay,  cotton,  coffee,  oatmeal,  &c.  be  explained  ?  In  what  manner  may 
phosphorus  and  charcoal  be  inflamed  ? 

*  See  Ann.  de  Chim. ;  and  Edinb.  Journ.  of  Science,  N.  S.  No.  8. 
t  See  Journ.  of  "Science,  ed.  at  JR..  I.,  vol.  x.  p.  454 ;  and  Ann.  of  Philos., 
vol.  xvi.  p.  390. 
J  Silliman's  Journ.  of  Science 


INFLUENCE  OF  HEAT  ON  SOLUTION. 


37 


and  atmospheric  air,  would  almost  instantly  take  fire.  The  pla- 
tina  becomes  heated,  presently  red  hot,  then  it  attains  a  white 
heat,  and  immediately  the  hydrogen  inflames,  and  the  combustion 
continues  as  loner  as  any  portion  of  the  combustible  elements  re- 
mains. Brewster  says  :  *'  In  this  case  the  minutely-divided  pla- 
tina  acted  upon  the  hydrogen  gas  in  the  same  manner  as  the 
minutely-divided  charcoal  acted  upon  common  air.  Heat  and 
combustion  were  produced  by  the  absorption  of  both  gases,  though 
in  the  one  case  the  effect  was  instantaneous,  and  in  the  other  was 
the  result  of  a  prolonged  absorption."* 

77.  This  property  of  spongy  platina  has  been  happily  applied 
to  a  purpose  of.much  practical  utility,  by  M.  Gay  Lussac,  in  the 
contrivance  of  a  lamp  for  the  production  of  instantaneous  light. 
Improvements  or  modifications  of  this  instrument  have  been  made 
by  Mr.  Garden  and  others  ;  but  the  principle  on  which  the  appa- 
ratus is  constructed  is  the  same  in  all,  and  they  consist  of  ar- 
rangements for  the  regulated  production  of  hydrogen  gas,  from 
the  solution  of  zinc  or  iron  in  diluted  sulphuric  acid,  and  by  open- 
ing a  stop-cock  throwing  a  current  of  the  gas  on  a  mass  of  spongy 
platina,  which  becoming  red-hot,  the  hydrogen  inflames,  and  af- 
fords the  means  for  lighting  a  taper. 

78.  One  form  of  Gay  Lussac's  ap- 
paratus is  seen  in  the  annexed  figure. 
A  glass  vase  containing  a  solution  of 
sulphuric  acid  in  the  proportion  of  one 
part  acid  to  15  or  20  of  water,  has  a  cover 
of  brass  resting  on  its  upper  rim,  to 
which  is  cemented  a  conical  glass  jar  of 
smaller  dimensions,  open  below  and  per- 
forated above,  for  the  escape  of  gas 
when  required.  From  a  brass  rod  on 
the  interior  of  this  second  jar,  is  sus- 
pended a  cylinder  of  zinc,  the  bottom  of 
which  is  nearly  as  low  as  that  of  the 
conical  jar.  A  stop  cock  above  the  brass 
plate  opens  a  communication  with  the  interior  glass  vessel,  and 
allows  the  hydrogen  gas  to  escape  through  a  small  pipe  or  nozzle, 
and  be  projected  on  a  bit  of  spongy  platina,  contained  in  a 
thimble-shaped  receptacle  near  the  periphery  of  the  lid,  when 
it  soon  becomes  red  hot,  and  ignites  the  jet  of  hydrogen  gas. 

79.  Numerous  experiments  were  made  by  MM.  Dulong  and 
Thenard,  with  a  view  to  elucidate  the  cause" of  the  inflammation 

What  is  the  nature  of  Dobereiner's  experiment  on  the  ignition  of  platina  ? 
What  explanation  of  the  result  has  been  attempted  ? 
How  has  Guy  Lussac  applied  to  practical  purposes  the  experiment  with 
spongy  platina? 

Describe  his  apparatus  ? 


1 


*  Sir  D.  Brewster's  Natural  Magic,  p.  318. 


38  CHEMISTRY. 

produced  by  the  contact  of  finely-divided  platina  with  hydrogen 
gas.  From  their  researches  it  appeared — 1.  That  palladium, 
rhodium,  and  iridium,  have  the  same  effect  on  the  gas  with  pla- 
tina; 2.  That  osmium  in  like  manner  produces  inflammation,  but 
requires  a  temperature  of  45°  centigrade,  and  gold  inflames  at 
120°  ;  3.  That  charcoal,  glass,  pumicestone,  and  porcelain,  have 
similar  effects,  but  at  temperatures  near  250° ;  4.  That  all  these 
bodies  lose  the  property  in  question  by  long  exposure  to  the  air, 
but  they  recover  it  on  being  calcined.* 

80.  Among  the  various  causes  of  spontaneous  combustion  that 
might  be  mentioned,  there  is  none  more  interesting  or  curious  than 
that  of  the  human  body,  many  instances  of  which  are  upon  record. 
But  the  subject  will  again  be  noticed,  in  treating  of  the  effect  of 
electricity  on  chemical  attraction,  and  therefore  need  not  be  intro- 
duced here. 

81.  Elevation  of  temperature  generally  promotes  the  chemical 
action  of  bodies.     Its  influence  in  many  cases  appears  to  depend 
on  the  diminution  of  cohesion,  or  the  separation  of  the  particles  of 
matter  by  heat,  as  when  expansion  or  liquefaction  takes  place.1 
But  its  effects  are  sometimes  more  complicated  and  obscure;  and 
the  phenomena  indicate  an  obvious  correspondence  between  heat 
and  electricity  or  galvanism.     A  remarkable  instance  of  the  in- 
fluence of  heat,  in  conjunction  with  light  on  the  chemical  union  of 
bodies,  may  be  pointed  out  in  the  production  of  muriatic  acid  from 
the  mixture  of  chlorine  and  hydrogen  gases,  noticed  above.  When 
the  proper  quantities  of  these  gases  required  to  form  the  compound 
are  mingled  in  a  glass  jar,  so  long  as  light  and  heat  are  excluded 
no  combination  takes  place,  but  if  the  mixture  be  exposed  to  the 
direct  rays  of  the  sun,  detonation  ensues,  and  muriatic  acid  gas  is 
formed  ;   and  the  same  effect  is  produced  by  introducing  into  the 
jar  a  lighted  taper,  or  passing  through  its  contents  an  electric  spark. 

82.  It  must  be  observed,  that,  though  elevation  of  temperature 
to  a  certain  extent  may  facilitate  the  chemical  union  of  bodies,  the 
effect  will  depend,  in  any  given  case,  on  the  adaptation  of  the  de- 
gree of  heat  to  the  particular  process.      Thus  mercury  exposed  to 
the  contact  of  atmospheric  air  at  the  temperature  of  nearly  680° 
Fahrenheit,  in  a  proper  vessel,  combines  with  oxygen  to  form  the 
red  oxide  of  mercury,  which  substance,  when  exposed  to  a  red 
heat,  1275°,  becomes  decomposed,  returning  to  the  state  of  metal- 
lic mercury  and  oxygen  gas. 

83.  Temperature  has  generally  a  great  influence  on  the  solvent 
"power  of  water,  and  also  on  that  of  other  liquids.     Hot  water  is 

What  four  resulls  did  Dulong  and  Thenard  obtain  from  their  experi- 
ments on  this  subject  ? 

What  effect  has  elevation  of  temperature  on  chemical  attraction? 

On  what  does  this  effect  appear  to  depend  ? 

What  remarkable  example  of  this  can  be  exhibited  ? 

What  diversity  of  effects  may  be  found  to  arise  from  different  degrees 
of  elevation  in  temperature? 

*  Pouillet  Elera.  de  Phys.,  vol.  i.  pp.  425,  426. 


INFLUENCE  OF  HEAT  ON  SOLUTION. 


39 


capable  of  holding  in  solution  larger  quantities  of  most  substances 
than  cold  water:  thus,  saltpetre,  or  nitrate  of  potash,  arid  chlorate 
of  potash,  are  much  more  readily  soluble  in  water  at  a  high  than 
at  a  low  temperature  ;  and  with  regard  to  many  other  saline  bodies 
the  dissolving  power  of  the  liquid  is  increased  by  augmentation  of 
temperature.  But  this  is  by  no  means  always  the  case.  Water 
cooled  to  near  the  freezing  point,  will  take  up  almost  double  the 
quantity  of  caustic  lime  that  can  be  held  in  solution  by  boiling 
water.  Glauber  salt,  or  sulphate  of  soda,  is  most  readily  soluble 
in  water  at  about  92°  Fahrenheit,] (33°  cent.,)  the  solvent  power 
of  water  with  respect  to  that  salt  increasing  with  the  augmentation 
of  heat  up  to  that  point,  after  which  it  diminishes  to  215°,  at  which 
temperature  nearly  the  same  relative  quantity  of  the  salt  will  be 
taken  up  as  at  87°.  Seleniate  of  soda  likewise  is  more  soluble 
at  92°  (33°  cent.)  than  at  a  higher  or  lower  temperature. 
Pans 


C  0°     10°     20°     30°    40°    50°    60°     70°    80°     90°    100°     110° 
F  32°   50°     68°     86°     104°  122°  140°  158°  176°  194°  212°     230° 
N.  P.  nitrate  of  potash.  S.  M.  sulphate  of  magnesia  (anhydrous.) 

S.  S.  sulphate  of  soda  (anhydrous.)     Chi.  B.  chloride  of  baryum  (anhydrous.) 
Ch.  Prn.  chloride  of  potassium.          Chi.  S.  chloride  of  sodium. 
Cht.  P.  chlorate  of  potash.  S.  B.  sulphate  of  barytes. 

S.  P.  sulphate  of  potash. 

What  effect  has  elevation  of  temperature  on  the  solvent  power  of  liquids  ? 

What  remarkable  exception  to  this  law  has  been  observed  ? 

At  what  temperature  will  water  dissolve  the  greatest  quantity  of  the 
sulphate  or  the  seleniate  of  soda  ? 

At  what  temperature  Fah.  would  a  given  quantity  of  water  dissolve  as 
much  chlorate  of  potash  as  it  would  of  the  sulphate  of  barytes  ?  [See  table.] 

What  number  of  parts  of  either  of  those  salts  would  100  parts  by  weight 
of  water  dissolve  at  that  temperature  ? 

Of  what  salt  will  water  dissolve  the  same  quantity  at  all  temperatures? 

At  what  temperatures  is  the  solvent  power  of  water  the  same  for  nitrate 
of  potash  as  for  sulphate  of  magnesia  ?  At  what  two  points  will  it  take  up 
erjnal  quantities  of  sulphate  of  soda  and  of  chloride  of  potassium  ? 


40  CHEMISTRY. 

84.  The  relation  between  temperature  and  solubility  will  be 
most  distinctly  perceived  from   the  inspection  of  the  preceding 
table.     The  vertical  line  of  figures  indicates  the  respective  por- 
tions  of  several  salts,  taken   up   by  100  parts  of  water,  and  the 
horizontal  line  of  figures  denotes  the  temperatures  of  which  the 
solutions  take  place.     The  line  which  is  marked  Chi.  S.,  shows 
the  solubility  of  chloride  of  sodium,  (common  salt,)  and  it  cuts 
the  perpendicular  lines  all  at  the  same  height  No.  37,  which  indi- 
cates that  one  hundred  parts  of  water  will  at  all  temperatures  dis- 
solve 37  parts  of  common  salt.  The  line  marked  Chi.  B.,  anhydrous 
chloride  of  baryum,  cuts  the  perpendicular  line  marked  0°  at  No. 
31,  that  which  is  marked  55°  at  No.  45,  and  that  marked  110°  at 
No.  61  .  hence  it   must  be  understood  that   100  parts  of  water 
will  take  up  31  parts  of  anhydrous  chloride  of  barynm  at  zero, 
45  parts  at  55°,  and  61  parts  at  110°.     The  line  marked  S.  S., 
sulphate  of  soda,   rises  to  33°  and  then  descends,  denoting  the 
sulphate  to  be  most  soluble  at  that  temperature,  as  above  stated. 
The  manner  in  which  the  various  influence  of  temperature  on 
other  salt  is  exhibited  in  this  table  will  be  sufficiently  obvious 
from  the  preceding  examples.* 

85.  (4.)  The  influence  of  electricity  on  chemical  processes,  attract- 
ed the  attention  of  philosophers  before  the  middle  of  the  last  century, 
when  it  was' ascertained  that  ether  might  be  fired   by  the  electric 
spark;  and  the  deflagration  of  spirit  of  wine,  fulminating  gold, 
and  some  other  inflammable  bodies,  was  soon  after  effected  by  the 
same  means.     More  recent  researches  evinced  the  possibility  of 
producing  the  combustion  of  iron  wire  by  exposing  it  to  the  shock  of 
an  electric  battery.   The  metal  is  thus  oxidated  in  the  same  manner 
as  by  the  violent  friction  caused  by  striking  fire  with  a  flint  and 
steel.     Other  metals,  as  well  as  iron,  may  be  made  to  undergo 
combustion  by  exposing  them  to  the  charge  of  a  battery  of  elec- 

1  trie  jars.  A  fine  gold  wire  may  thus  be  burnt,  yielding  a  bluish- 
white  flame,  and  the  product  will  be  a  protoxide  of  gold,  in  the 
state  of  an  impalpable  purple  powder.  Silver  wire  may  in  the 
same  manner  be  made  to  burn  with  a  green  flame ;  and  corres- 
ponding phenomena  take  place  with  the  other  metals. 

86.  The  effect  of  the  electricity  of  excited  jars  on  the  combi- 
nation of  gases,  was  the  subject  of  experiments  by  Mr.  Waltire, 
Dr.  Priestly,  and  Mr.  Cavendish  ;  and  the  latter,  about  1776,  thus 

How  early  was  the  connection  between  electrical  and  chemical  actions 
discovered  ? 

What  observations  led  to  this  discovery  ? 

What  effect  has  a  discharge  of  electricity  on  fine  iron  wire  ? 

When  and  by  whom  was  the  action  of  electricity  on  gases  investigated  ? 

*  This  Table  is  taken  from  Mitscherlich's  Introduction  to  Chemistry 
(Germ.),  Berlin,  1832  8vo.  vol.  i.  p.  287.  The  temperatures  are  given  ac- 
cording to  the  scale  of  both  the  centigrade  and  Fahrenheit's  thermometer. 
In  this  arid  all  similar  cases  the  student  will  change  degrees  centigrade 
into  those  of  Fah.  by  taking  9-5ths  of  the  number  of  the  former  and  ad- 
ding to  it  32°.— Ed. 


ELECTRICITY.  41 

produced  water,  by  firing  a  mixture  of  hydrogen  gas  and  atmos- 
pheric air ;  and  lie  also  obtained  nitric  acid,  by  employing  elec- 
tricity to  determine  the  combination  of  oxygen  and  nitrogen.  In 
1781,  Lavoisier  and  Laplace  made  important  experiments  on  the 
development  of  electricity  in  the  evaporation  of  liquids,  and  the 
solution  of  solids,  as  when  metals  are  dissolved  in  diluted  acids; 
and  from  the  latter  researches  of  Becquerel,  at  Paris,  it  may  be 
concluded  that  electricity  is  evolved  in  all  cases  of  chemical  so- 
lution.* 

87.  The  relation  between  electrical  and  chemical  attraction  has 
been  confirmed  by  the  discovery  of  Galvanic  or  Voltaic  electricity, 
the  effects  of  which  manifestly  depend  on  the  same  peculiar  energy 
that  gives  rise  to  the  phenomena  of  the  Leyden  phial.    It  has  been 
ascertained  that  chemical  decompositions  and  combinations  can 
be  accomplished  more  easily  and  readily  by  means  of  the  Voltaic 
pile  or  battery,  than  by  the  aid  of  an  electrical  machine  and  the 
apparatus  belonging  to  it. 

88.  Some  notice  has  been  taken  of  the  chemical  power  of  the 
Voltaic  battery  in  the  preceding  volume  of  this  work,  to  which  the 
reader  is  referred  for  an  account  of  the  construction  of  Galvanic 
or  Voltaic  troughs,  for  the  reception  of  zinc  and  copper  plates 
with  an  interposed  fluid,  which  may  be  used  for  the  production 
of  various  chemical  phenomena.*     With  such  a  Voltaic  ba'ttery, 
water  and  other  chemical   compounds  in  a  fluid  state  may  be 
decomposed,  merely  by  dipping  the  extremities  of  two  wires 
communicating  with  the  opposite  poles  of  the  battery  beneath  the 
surface  of  the  mass  of  fluid,  and  thus  causing  the  latter  to  form 
part  of  a  Voltaic  circle.   The  decomposition  of  a  saline  substance, 
as   sulphate   of  soda,  may   be    thus  effected,  by  using  a  glass 
tube    bent   so    that    the    angular   part   may   fit   into  a  common 
wine-glass,  which  will  serve  to  support  it.     Then  into  the  open 
ends  of  the  tube  insert  two  wires  or  strips  of  platina'foil,  which 
may  reaoh  nearly  to  the  angle,  but  must  not  come  in  contact ;   fill 
the  tube  with  a  solution  of  the  sulphate,  and  connect  one  of  the 
wires  with  the  zinc  or  negative  pole,  and  the  other  with  the  cop- 
per or  positive  pole,  of  a  Voltaic  battery,  and  the  salt  will  be 
decomposed,  the  alkali  or  soda  collecting  in  the  leg  of  the  inverted 
siphon   or  tube  in  connexion  with  the  negative  pole,  and    the 
sulphuric  acid  in  the  part  of  the  tube  connected  with  the  positive 
pole. 

89.  In  all   cases  of  decomposition   by  means   of  electricity, 
whether  derived  from  the  friction  of  glass,  as  by  the  common 

What  general  truth  in  regard  to  this  subject  appears  to  result  from  the 
experiments  of  Lavoisier,  Laplace  and  Becquerel? 

What  aid  has  the  discovery  of  Galvani  afforded  in  the  study  of  electro- 
chemistry ? 

Describe  the  manner  in  which  a  saline  substance  may  be  decomposed 
by  Galvanic  electricity  ? 

*  See  Scientific  Class  Book,  part  i.  page  440  to  446  inclusive. 
D  2. 


42  CHEMISTRY. 

machine,  or  from  the  contact  of  perfect  and  imperfect  conductors, 
as  in  the  Voltaic  battery,  it  will  be  found  that  one  of  the  constitu- 
ent elements  of  the  body  undergoing1  decomposition  will  be  evolved 
at  the  negative  pole,  and  the  other  at  the  positive.  Hence  it  must 
be  concluded,  that  the  bodies  thus  separating  must,  with  respect 
to  each  other,  be  actuated  by  opposite  kinds  of  electricity ;  and 
the  observation  of  this  phenomenon  has  led  to  an  arrangement 
of  bodies  in  two  classes,  namely,  electro-negative  and  electro- 
positive substances;,  all  those  kinds  of  matter  which  are-attract- 
ed by  the  positive  pole  of  a  Galvanic  battery  being  included  in 
the  former  class,  and  all  those  attracted  by  the  negative  pole  in 
the  latter  class. 


91.  Thus  in  the  decomposition  of  water  in  the  apparatus  repre- 
sented in  the  accompanying  figure,  the  wire  Z  connected  with  the 
zinc  plate  or  pole  of  a  Voltaic  apparatus,  &c.,  with  the  negative 
there  will  be  from  the  end  of  the  platina  wire  P,  a  developement  ol 
oxygen,  and  from  N  an  escape  of  double  the  bulk  of  hydrogen,  both 
of  which  rising  into  their  respective  branches  of  the  tube  will  be 
collected  at  O  and  at  H.     But  though  the  distinction  between  the 
electro-negative  and  the  electro-positive  bodies  is  sufficiently  ob- 
vious in  the  decomposition   of  compounds  of  two  bodies  of  the 
opposite  classes,  yet  it  requires  modification  when  applied  to  com- 
pounds resulting  from  the  union  of  two  electro-negative  or  two 
electro-positive  bodies  respectively. 

92.  Oxygen  when  separated  from  its  combination  with  other 
simple  bodies  by  electricity,  is  always  evolved  at  the  positive 
pole;  and  it  may  therefore  be  concluded  that  it  is  the  most  electro- 
negative of  all   known  substances.1   It  forms  compounds  with 
chlorine  and  the  other  electro-negative  elements,  constituting  the 
chloric,  iodic,  and  bromic  acids ;  and  when  these  are  decomposed 
by  the  Voltaic  battery,  the  oxygen  is  evolved  at  the  positive  pole, 
and  the  chlorine,  iodine,  or  bromine,  at  the  negative  pole.    In  the 
same  manner  the  electro-positive  elements  enter  into  union  with 

What  remarkable  circumstance  always  attends  decomposition  by  means 
of  electricity  ? 

What  inference  are  we  allowed  to  draw  from  this  fact? 
What  constitute  the  class  of  electro-negative  bodies  ? 
What  the  electro-positive  ? 

To  which  pole  does  the  electro-negative  matter  pass  ? 
Under  what  circumstances  will  it  disappear? 
Describe  the  apparatus  for  decomposing  water? 
Which  is  the  most  electro-negative  of  known  bodies? 


EFFECTS  OF  ELECTRICITY.  43 

each  other,  forming-  compounds  which,  when  electrically  decom- 
posed, manifestly  indicate  gradations  of  electric  energy  among 
them.  Sulphur,  which,  with  respect  to  oxygen,  chlorine,  iodine, 
and  bromine,  and  probably  some  other  simple  bodies,  is  electro- 
positive, becomes  electro-negative  when  combined  with  hydrogen  ; 
for  when  a  compound  of  sulphur  and  hydrogen  is  decomposed  by 
Voltaic  electricity,  the  sulphur  appears  at  the  positive  pole,  and 
the  hydrogen  at  the  negative.  The  sulphurets  of  carbon,  phos- 
phorus,^and  many,  if  not  all  the  metals,  exhibit  similar  phenomena. 

93.  Hence  it  appears,  that  sulphur  is  only  relatively  electro- 
positive, as  in  its  combinations  with  oxygen,  while  it  becomes 
electro-negative  by  being  united  to  hydrogen,  carbon,  phosphorus, 
and  the  metals.*     Experiments  are  wanting  to  enable  us  to  as- 
certain how  far  the  electricity  of  all  bodies  is  merely  relative,  or 
whether  the  disposition  of  bodies  to  be  attracted  by  the  positive 
pole  of  a  Voltaic  pile  or  battery,  which  seems  to  exist  in  the 
strongest   degree   in   oxygen,  descends*  by  a  regular  gradation 
throughout  the  catalogue  jj£    \jstances.    We  may  remark, 
however,  that  while  th^6ejlffi*»*r  been  designated  electro- 
negative bodies  display  the  highest  electro-chemical  energy,  or 
tendency  to  be  attracted  frbm  their  compounds  by  the  positively 
electrified  wire,  hydrogen  and  some  of  the  metals  seem  to  have  in 
an  extreme  degree  the  contrary  disposition  to  be  attracted  by  the 
negative  wire. 

94.  The  influence  of  electric  attraction  on  the  chemical  affini- 
ties of  bodies  is  especially  observable  in  the  combination  of  metals 
with  oxygen,  and  in  the  decomposition  of  metallic  salts.  Pure  pot- 
ash or  vegetable  alkali  is  a  compound  of  oxygen  with  the  metal 
called  potassium  ;  and  the  affinity  between  those  bodies  is  so 
strong  that  chemists  were  long  baffled  in  their  attempts  to  effect 
their  decomposition.  >  At  length  Sir  H.  Davy  succeeded,  by  ex- 
posing moistened  potash  to  the  action  of  a  Voltaic  battery ;  thus 
augmenting  the  respective  electro-chemical  energies  of  the  oxy- 
gen and  the  metal,  they  were  severally  attracted  by  the  wires 
connected  with  the  opposite  poles,  and  the  former  was  evolved 
at  the  positive,  while  the  latter  (the  metallic  potassium)  made 
its  appearance  at  the  negative  pole. 

95.  Some  other  curious  and  interesting  phenomena,  relating  to 

What  is  the  relative  electric  condition  of  sulphur  compared  with  that 
of  hydrogen,  carbon,  phosphurus,  and  metals? 

What  substances  appear  in  the  highest  degree  electro-positive  ? 

In  what  cases  is  electric  attraction  most  remarkahle  in  modifying  che- 
mical action  ? 

What  striking  example  of  this  is  afforded  in  the  history  of  chemistry  ? 

With  which  electrical  pole  must  a  melal  capable  of  oxidation  by  an  acid 
be  connected  in  order  to  prevent  that  effect  ? 

*  For  some  interesting  and  curious  observations  on  the  electro-chemical 
proper!  ies  of  sulphur,  see  "  Report  on  the  Recent  Progress  and  Present 
State  of  Chemical  Science.  By  James  F.  W.  Johnston,  A.  M."  Reports  of 
the  British  Association  for  the  Advancement  of  Science,  1832,  pp.  440-442. 


44  CHEMISTRY. 

the  affinities  between  metals  and  acids  may  here  be  noticed,  as 
tending  to  illustrate  the  influence  of  electricity  on  the  chemical 
union  of  bodies.  Metals  may  be  immersed  in  liquid  acids,  which 
under  common  circumstances  reduce  them  to  the  state  of  oxides, 
but  the  action  of  such  acids  may  be  suspended  by  rendering  the 
metal  electro-negative,  or  placing  it  in  communication  with  the 
negative  pole  of  a  Voltaic  battery^  If  two  polished  plates  of  iron 
or  copper  be  plunged  in  diluted  sulphuric  acid,  one  of  the 
plates  of  either  metal  having  been  connected  with  the  positive 
wire  of  a  Voltaic  battery,  and  the  other  plate  of  the  metal  con- 
nected with  the  negative  wire,  it  will  presently  be  perceived  that 
the  plate  rendered  positive  will  become  tarnished  and  corroded  by 
the  action  of  the  acid,  while  it  will  take  no  effect  on  the  negative 
plate,  which  will  remain  as  bright  as  before  immersion.  Silver 
unprotected  is  readily  acted  on  by  diluted  nitric  acid,  which  dis- 
solves the  metal  placed  in  contact  with  it,  just  as  sulphuric  acid 
dissolves  iron  ;  but  if  the  silver  be  rendered  electro-negativej  it  is 
enabled  to  resist  the  pow  of  the  acid,  even  when  long  immersed 
in  it. 

96.  As  electricity  is  evolved  by  the  contact  of  different  metals 
with  water  and  other  fluids,  hence  it  sometimes  happens  that  two 
metals  connected  together  and  plunged  in  an  acid  or  saline  liquid, 
may  form  a  kind  of  miniature  Voltaic  apparatus,  and  the  common  ef- 
fect of  the  menstruum  is  augmented  with  respect  to  one  of  the 
metals,  and  controlled  or  suspended  with  respect  to  the  other. 
Let  a  small  piece  of  sheet  copper  be  dropped  into  a  tumbler-glass, 
containing  two  drams  of  nitric  acid  diluted  with  ten  drams  of 
water,  and  in  a  short  time  enough  of  the  metal  will  be  dissolved 
to  give  a  bluish  tint  to  the  liquid  :  the  addition  of  a  few  drops  of 
liquor  of  ammonia  will  increase  considerably  the  depth  of  the 
colour,  and  render  it  more  perceptible.  Now,  if  a  plate  of  copper 
united  to  one  of  zinc  be  immersed  in  an  acid  mixture  of  the  same 
kind,  it  will  not  act  at  all  on  the  copper,  but  will  more  rapidly 
dissolve  the  zinc  than  if  that  metal  were  plunged  in  it  alone. 
That  the  copper  in  this  case  is  protected  by  the  zinc  from  the 
action  of  the  acid  menstruum,  will  appear  on  dropping  into  it  liquor 
of  ammonia,  as  before ;  for  it  will  now  produce  no  effect,  since 
though  that  alkali  communicates  a  blue  or  purple  colour  to  solu- 
tions of  copper,  no  such  change  takes  place  on  adding  it  to  those 
of  zinc.  Iron  may  thus  be  shielded  from  the  dissolving  power 
of  acids,  as  will  appear  by  immersing  a  polished  plate  of  that 
metal,  with  one  of  zinc  attached  to  it,  in  any  weak  acid,  as  the 
muriatic,  (spirit  of  salt,)  largely  diluted  with  water ;  for  while  the 
zinc  will  undergo  solution,  the  plate  of  iron  will  remain  bright 
and  untarnished,  though  if  plunged  in  the  diluted  acid  alone,  it 
would  be  acted  upon  immediately. 

How  may  silver  be  preserved  from  corrosion  when  immersed  in  nitric  acid? 
How  may  the  preservation  of  copper  from  corrosion  in  salt  water  be  ef- 
fected ? 

How  is  it  proved  that  in  this  case  no  copper  is  dissolved  ? 


METALLIC  CRYSTALLIZATION.  45 

97.  On  the  observation  of  the  electro-chemical  effects  of  the 
contact  of  metals  was  founded  a  method,  proposed  by  Sir  H. 
Davy,  for  preserving  the  copper  sheathing  of  ships  from  the  cor- 
roding1 action  of  sea-water.     It  has  long  been  the  custom  among 
ship-builders  to  cover  the  outer  surface  of  the  hulls  of  large 
vessels  with  sheets  of  copper,  the  durability  and  consequent  ad- 
vantages of  which  were  found  to  be  greatly  diminished  by  the 
action  of  the  saline  matters  contained  in  the  sea-water  on  the 
metal,  producing  oxidation,  corrosion,  and  decay. 

98.  The  plan  proposed  for  the  prevention  of  these  injurious 
effects  of  the  exposure  of  the  copper  sheathing  of  ships  to  the  ac- 
tion of  sea-water  during  long  voyages,  consisted  in  fixing  to  the 
surface  of  the  copper  plates  of  zinc  or  iron,  called  protectors,  the 
effect  of  which  was  to  render  the  copper  electro-negative,  and  thus 
prevent  it  from  attracting  oxygen  from  the  water,  or  substances 
held  in  solution  in  it ;  the  protectors  themselves  becoming  oxi- 
dated and  greatly  dissolved,  while  the  copper  was  preserved. 
Experiments  conducted  on  a  small  scale,  and  for  a  very  limited 
period,   showed   that  the  effect  intended  might  certainly  be  pro- 
duced, but  it  was  found  that  when  a  copper-bottomed  vessel  was 
armed  with  Davy's  protectors,  though  the  copper  in  the  course 
of  a  long  voyage  was  prevented  by  its  electro-negative  energy 
from  becoming  oxidized,  yet  from  the  same  cause  it  powerfully 
attracted  from  the  sea-water  earthy  matter,  such  as  lime,  magne- 
sia, and  other  electro-positive  bodies  dissolved  in  it,  and  thus  ac- 
quired a  rough  coating,  to  which  marine  plants  and  animals  be- 
came attached  so  abundantly  as  to  prove  a  serious  inconvenience. 
The  failure  of  this  plan,  under  such  circumstances,  only  serves 
more  strikingly  to  illustrate  the  principle  under  consideration. 

99.  In  the  whole  range  of  experimental  chemistry  there  are  few 
phenomena  more  curious  or  beautiful  than  those  exhibited  by  metal- 
lic arborizations,  or  the  depositions  of  crystallized  metals,  from  the 
decomposition  of  metallic  salts.     An  attention  to  the  manner  in 
which  such  experiments  are  conducted  will  enable  us  to  trace  a 
strong  analogy  between  those  processes,  and  some  of  the  instances 
of  electro-chemical  decomposition  previously  adduced. 

100.  The  production  of  the  Tree  of  Diana,  (Arbor  Dianas,)  a 
process  said  to  have  been  invented  by  Lemery,  a  French  chemist, 
in  the  beginning  of  the  last  century,  must  have  excited  the  admi- 
ration of  many  persons  quite  unacquainted  with  chemistry.     To 
form  this  crystallization,  let  six  drams  of  a  saturated  solution  of 
pure  silver  in  nitric  acid,  and  four  drams  of  a  similar  solution  of 
mercury  in  the  same  acid,  be  diluted  with  five  ounces  of  distilled 
water,  and  poured  into  a  small  decanter  or  glass  phial ;  then  com- 
pose an  amalgam,  by  mixing  one  part  of  finely-divided  silver 

By  whom  was  the  application  of  these  facts  to  practical  purposes  sug- 
gested ?     Explain  the  purpose  to  which  they  were  applied, 
f  n  what  manner  is  a  ship's  copper  protected  from  corrosion  ? 
What  inconvenience  arose  from  the  use  of  Davy's  protectors? 
Explain  the  experiment  called  Arbor  Dianas  ? 


46  CHEMISTRY. 

with  seven  parts  of  mercury,  and  place  a  small  lump  of  it  at  the 
bottom  of  the  bottle,  which  must  be  kept  quite  still.  In  a  short 
time  the  surface  of  the  amalgam  will  be  covered  with  minute 
filaments  of  silver,  and  after  standing  about  forty-eight  hours,  the 
solution  will  deposit  all  its  silver,  in  the  form  of  brilliant  abores- 
cent  crystals,  springing  like  a  glittering  shrub  from  the  bottom 
of  the  vessel.* 

101.  An  experiment  of  a  very  similar  nature,  which  requires 
less  skill  and  attention  in  its  management  than  the  preceding,  is 
the  reduction  of  lead  in  the  crystalline  state  from  its  combination 
with  acetic  acid,  by  means  of  zinc.     This  may  be  effected  simply 
by  suspending  a  lump  of  zinc  in  a  solution  of  acetate  of  lead, 
commonly  called  sugar  of  lead,  in  the  proportion  of  two  drams 
of  the  salt  to -six  ounces  of  water,  contained  in  a  glass  phial  or 
flask.   In  this  case  the  revived  metal  is  deposited  more  slowly, 
forming  shining  foliated  crystals,  first  covering  the  surface  of  the 
zinc  and  then  extending  from  it  towards  the  bottom  of  the  phial. 
Here  the  electro-positive  zinc  attracts  oxygen  from  the  relatively 
electro-negative  lead,  and  forms  acetate  of  zinc,  while  the  lead  is 
set  free. 

102.  The  decomposition  of  metallic  salts  may  be  effected  by 
means  of  electro-positive  bodies  not  of  a  metallic  nature,  giving 
rise  to  appearances  much  resembling  those  already  described.    If  a 
lump  of  charcoal  be  suspended  in  a  solution  of  sulphate  of  copper, 
the  metal  will  be  gradually  revived,  forming  small  crystals  on  the 
surface  of  the  charcoal.    And  a  stick  of  phosphorus  immersed  in 
a  solution  of  nitrate  of  silver  will  become  covered  with  a  crystal- 
line incrustation  of  the  reduced  metal. 

103.  The  following  method  of  forming  metallic  arborizations 
on  the  surface  of  glass,  so  as  to  produce  a  pleasing  effect,  was 
published  a  few  years  ago  in  a  French  journal.     Place  a  few 
filings  of  copper  arid  of  iron  on  a  glass  plate,  at  a  certain  distance 
one  from  the  other.     Then  drop  a  little  nitrate  of  silver  (in- solu- 
tion) on<each  parcel :  the  silver  will  soon  begin  to  be  precipitated, 

In  what  manner  is  this  effect  to  be  explained  ? 

How  may  the  crystallization  of  lead  from  an  acid  solution  be  exhibited  ? 
What  other  mode  may  be  employed  to  exhibit  the  effect  of  electro-posi- 
tive and  electro-negative  bodies  on  each  other  ? 

*  Mr.Brande  says:  "The  principal  use  of  the  addition  of  mercury  to  the 
solution,  and  of  silver  to  the  precipitating  mercury,  is  to  give  a  degree  of 
tenacity  to  the  arborescent  deposit  of  crystals,  which  prevents  their  falling 
to  the  bottom  of  the  flask." — Manual  of  Chemistry,  3d  edit.  1830,  vol.  ii.  p. 
184.  It  seems  difficult,  however,  to  conceive  how  the  mercury  that  re- 
mains ia  solution,  or  the  divided  silver  in  the  amalgam,  can  communicate 
tenacity  to  the  crystalline  deposit;  and  though  the  silver  in  the  amalgam 
may  serve  as  a  sort  of  nucleus  for  the  newly-formed  metal,  yet  it  is  most 
probable  that  the  nitrate  of  mercurv  and  the  metallic  silver  contribute  to 
the  success  of  the  experiment  chiefly  by  forming  a  Voltaic  circle,  or  com- 
bination of  electro-positive  and  electro-negative  bodies,  in  consequence  of 
which  the  electro-positive  metal,  mercury,  is  enabled  the  more  easily  to 
decompose  the  nitrate  of  silver. 


.ANIMAL  ELECTRICITY.  47 

while  the  iron  and  copper  are  oxidized  and  become  coloured. 
Now  with  a  small  pointed  stick  the  metallic  ramifications  may 
be  arranged  in  any  figures,  and  the  flame  of  a  taper  held  under 
the  plate  will  promote  the  evaporation  of  the  liquid,  facilitate 
the  mutual  action  of  the  metals,  and  by  blackening  the  under 
side  of  the  plate,  form  a  sort  of  ground  for  the  design  traced  out.* 

104.  In  this  and  many  other  processes  of  a  corresponding  cha- 
racter, the  effects  may  with  probability  be  attributed  to  the  con- 
trast of  the  electro-positive  and  electro-negative  energies  of  the 
bodies  brought  within  the  sphere  of  each  other's  action.  .  And 
though  many  topics  of  research  with  regard  to  electro-chemistry 
remain  for   investigation,   it   may  be  concluded   from   what   is 
already  known,  that  bodies  attracting  each  other  to  form  chemical 
compounds  will  always  exhibit  opposite  states  of  electricity,  and 
compounds  may  be    decomposed  or  combinations  prevented  by 
altering  the  relative  electricities  of  the  bodies  whose  union  is  thus 
interrupted. 

105.  Some  writers  have  considered  electricity  as  the  general 
cause  of  combustion ;  and  the  recent  discoveries  of  philosophers 
relative  to  the  intimate  connection  between  electricity,  magnetism, 
and  heat,f  afford  grounds  for  concluding  that  the  peculiar  energy 
which  gives  rise  to  electric  phenomena,  may  extend  its  influence  to 
all  cases  of  chemical  combination,  and  especially  to  those  which 
are  accompanied  by  the  extrication  of  light  and  heat.:f:     In  illus- 
trating the  third  law  of  chemical  affinity,  or  that  which  relates  to 
the  influence  of  temperature,  examples  have  been  given  of  cases 
of  spontaneous  combustion,  which  are  traced  to  the  evolution  of 
heat,  in  consequence  of  the  absorption  of  atmospheric  air,  or  the 
oxygenous  portion  of  it,  by  large  masses  of  combustible  matter.§ 
That  electricity  is  concerned  in  the  production  of  these  pheno- 
mena is  at  least  highly  probable,  thougfc  it  may  be  difficult  to 
determine  its  mode  of  action.    In  the  still  more  remarkable  and  in- 
teresting cases  of  the  spontaneous  combustion  of  the  human  body, 
of  which,  unfortunately,  there  are  many  perfectly  authenticated  on 
record,  circumstances  may  be  pointed  out  which  strongly  indicate 
the  influence  of  electricity. 

How  may  the  surface  of  glass  be  coated  with  metallic  deposits  ? 

What  may  be  inferred  from  facts  already  known,  in  regard  to  the  electri- 
cal states  of  bodies  acting  chemically  on  each  other  ? 

What  may  we  conclude  with  respect  to  electro-chemical  action  from  the 
discoveries  in  other  departments  of  science  ? 

*  Journal  of  Science,  ed.  at  R.  Inst.,  vol.  x.  p.  181 ;  from  "  Annales  de 
Chimie." 

t  See  Scientific  Class  Book,  pt.  i.  pp.  449,  450. 

t  "  Combustion,"  observes  Mr.  Brande,  "may  be  connected  with  the 
electrical  energies  of  bodies ;  for  all  bodies  which  powerfully  act  upon 
each  other  are  in  the  opposite  electrical  states  of  positive  and  negative ; 
and  the  evolution  of  heat  and  light  may  depend  upon  the  annihilation  of 
these  opposite  states,  which  happens  when  they  combine." — Man.  of  Chem 
vol.  i.  p.  143. 

$  See  above  Nos.  72  to  81  inclusive. 


48  CHEMISTRY. 

106.  The  evolution  of  electric  light  from  the  bodies  of  living 
animals,  has  been  noticed  by  several  writers ;  and  though  such 
luminous  appearances  often  take  place  without  inflammation,  it 
may  be  readily  conceived  that  the  electricity  thus  evolved,  either 
owing  to  its  extraordinary  intensity  or  to  the  presence  of  highly 
inflammable  matter,  might  excite  combustion,  and  cause  the  de- 
struction of  a  human  body,  as  in  the  cases  in  question. 

107.  Among  the  instances  of  spontaneous  combustion  com- 
mencing during  life  in  the  human  subject,  that  of  the  Countess 
Cornelia  Zangari  and  Bandi,  of  Cesena,  has  perhaps  been  most 
frequently  quoted,  and  is  therefore  best  known.     The  circum- 
stances of  this  appalling  accident  were  published  in  Italy,  by 
Signor  Bianchini,  of  Verona,  and  subsequently  (in  1745)  by  Dr. 
Cromwell  Mortimer,  in  the  London  "  Philosophical  Transactions." 
This  lady,  who  was  sixty-two  years  of  age,  having  been  left  one 
night  by  her  attendant  in  bed  asleep,  was  found  the  next  morning  on 
the  floor  of  the  room  reduced  to  a  heap  of  ashes,  except  her  arms 
and  legs,  and  part  of  the  head.     The  air  of  the  apartment  was 
loaded  with  fine  soot,  which  had  a  noisome  smell.     The  bed  was 
not  damaged,  and  the  bed-clothes  were  lifted  on  one  side,  as 
usual  by  a  person  getting  out  of  bed.     Neither  the  floor  nor  fur- 
niture were  injured   by  fire,  the  combustion  manifestly  having 
been  excited  by  causes  acting  solely  on  the  body,  and  being  en- 
tirely confined  to  it.     The  countess,  it  seems,  was  accustomed, 
when  she  felt  indisposed,  to  bathe  her  body  with  camphorated 
spirit  of  wine. 

108.  Mr.  Wilmer,  an  eminent  surgeon  of  Coventry,  England, 
published  an  account  of  a  similar  occurrence,  on  which  he  had  an 
opportunity  for  making  observations.    Mary  Clues,  fifty  years  of 
age,  was  much  addicted  to  intoxication  ;  and  for  about  a  year  be- 
fore her  death,  scarcely  a  day  had  passed  in  the  course  of  which 
she  had  not  drunk  at  least  half  a  pint  of  rum  or  anniseed  water. 
Her  health  gradually  declined,  and  about  the  beginning  of  Fe- 
bruary, 1773,  she  was  attacked  by  jaundice  and  confined  to  bed. 
She  still  continued  her  habit  of  drinking  spirits  every  day,  and 
smoking  a  pipe  of  tobacco.     On  Saturday  morning,  March  1st, 
having  risen,  she  fell  on  the  floor,  and  being  too  weak  to  get  up, 
she  remained  lying  there  till  some  person  came  in  and  helped  her 
into  bed.    The  following  night,  she  requested  to  be  left  alone,  and 
a  woman  who  was  with  her  quitted  her  at  eleven  o'clock,  having 
shut  the  door  and  locked  it  according  to  custom.     At  half  after 
five  in  the  morning  smoke  was  observed  issuing  from  the  window, 
and  the  room-door  being  speedily  broken  open,  some  flames  which 
were  in  the  room  were  soon  extinguished.     Between  the  bed  and 
the  fireplace  were  found  the  remains  of  the  unfortunate  woman. 
One  leg  and  thigh  were  still  entire  ;  but  nothing  was  left  of  the 

What  fact  in.  regard  to  living  bodies  may  aid  in  forming  an  opinion  of 
the  cause  of  spontaneous  combustion  in  human  beings  ? 
What  account  is  given  of  the  Countess  of  Zangari's  case  ? 
What  is  the  history  of  that  of  Mary  Clues  ? 


SPONTANEOUS  COMBUSTION  OF  HUMAN  BODIES.  49 

skin,  muscles,  or  intestines.  The  bones  of  the  skull,  body,  and  arms, 
were  wholly  calcined,  and  covered  with  whitish  ashes.  The  side 
of  the  bedstead  next  to  the  chimney  was  slightly  burned  ;  but  the 
feather-bed  and  clothes  were  uninjured.  The  walls  and  every 
thing  in  the  room  were  blackened,  and  the  air  filled  with  a  very 
disagreeable  vapour,  though  nothing  except  the  body  exhibited 
any  strong  traces  of  fire. 

109^  A  case  of  spontaneous  combustion  is  related  in  the  "  Me- 
thodist Magazine"  for  1809,  on  the  authority  of  Mr.  Wood,  a 
Wesleyan  minister,  residing  at  Limerick,  Ireland,  in  which  the 
inflammation  appears  to  have  been  more  violent  and  rapidly  de- 
structive than  in  the  foregoinginstances.  Mr.  O'Neil,  keeper  of  the 
Five  Pounds  Almshouses,  in  the  city  of  Limerick,  was  awakened 
about  two  o'clock  in  the  morning  by  a  person  knocking  at  his  bed- 
room door,  upon  which  he  rose,  and  at  the  request  of  the  person 
who  knocked,  went  with  him  into  his  apartment,  wrhich  was 
under  the  room  occupied  by  a  Mrs.  Peacock.  There  they  found 
on  the  floor  a  dead  body,  burning  with  fire,  as  red  as  copper,  and 
which  had  dropped  through  the  ceiling ;  for  on  looking  up,  a  hole 
somewhat  the  shape  of  the  body  was  perceived,  the  floor  and 
rafters  above  having  been  destroyed.  M.  O'Neil  immediately  ran 
up  stairs,  and  having  burst  open  the  door  of  Mrs.  Peacock's  room, 
saw  the  aperture  in  the  middle  of  the  floor,  and  the  boards  still 
burning.  Having  with  assistance  quenched  the  fire  about  the 
hole,  he  endeavoured  to  discover  by  what  means  the  body  had 
taken  fire,  but  could  find  no  cause.  There  was  no  candle  or  can- 
dlestick near  the  place ;  no  fire  in  the  grate,  but  what  was  raked 
up  in  the  ashes  in  the  usual  manner  of  preserving  fire  through  the 
night.  The  room  was  examined,  and  nothing  had  taken  fire 
except  that  part  of  the  floor  through  which  the  body  had  fallen  : 
even  a  small  basket  of  twigs,  and  a  small  trunk  of  dry  wood 
which  lay  near  the  hole,  escaped  untouched  by  the  fire. 

110.  In  most  of  the  various  cases  of  spontaneous  combustion, 
more  or  less  circumstantially  related  by  different  writers,  imme- 
diate death  was  the  consequence,  or  at  least  life  had  become  ex- 
tinct before  the  miserable  fate  of  the  victim  was  discovered.  It 
appears,  however,  that  death,  or  at  all  events  immediate  death, 
is  not  always  the  result  of  an  accident  of  this  nature.  The  fol- 
lowing instance  of  spontaneous  combustion  is  interesting,  as  being 
one  in  which  the  party  escaped  destruction,  and  though  it  is  but 
imperfectly  related,  yet  it  seems  deserving  of  attention.  It  may 
be  found  in  a  "  Treatise  on  the  Climate,  Soil,  and  Rivers  of  Eng- 
land," published  by  Dr.  Charles  Claromont,  a  physician,  who 
was  a  native  of  Lorraine,  and  resided  in  England  in  the  reign  of 
Charles  II. 

Were  other  materials  found  affected  by  the  combustion  in  either  of 
these  cases? 

What  remarkable  circumstances  accompanied  the  combustion  in  the 
case  of  Mrs.  Peacock  ?  In  what  state  have  the  sufferers  by  such  occur- 
rences generally  been  discovered  ? 

E 


50  CHEMISTRY. 

111.  Two  citizens  of  Loudun,  near  Poitiers,  in  France,  having 
taken  a  walk  into  the  country,  visited  a  noble  friend,  and  meeting 
with  companions,  joined  them  in  a  game  with  a  ball.*  After 
playing  some  time  they  took  refreshment,  walked  out,  and  then 
played  again.  They  supped  together  pleasantly  and  merrily,  but 
no  one  drank  beyond  the  bounds  of  reason.  At  length,  night 
coming  on,  the  others  returned  to  the  town,  and  the  two  citizens 
remained  to  lodge  with  their  friend.  Retiring  to  their  chamber, 
they  performed  their  devotions,  undressed  themselves,  and  went 
to  bed.  But  they  had  scarcely  settled  themselves  in  bed,  when 
one  of  them,  in  terrible  alarm,  exclaimed  that  he  was  on  fire  :  and 
truly  his  breast  and  beard  taking  fire,  began  to  burn  so  that  a  part 
of  his  shirt  was  reduced  to  ashes,  his  bosom  and  chin  were 
scorched,  and  the  flame  could  scarcely  be  extinguished.  He 
would  doubtless  have  been  destroyed  by  the  conflagration,  if 
means  had  not  been  at  hand  to  suppress  it.  Dr.  Claromont  says 
he  saw  the  man  afterwards,  with  traces  of  the  injury  on  his  bosom 
and  face ;  and  he  learned,  from  particular  inquiry,  that  the  com- 
bustion could  not  have  been  caused  by  lightning,  nor  by  the  ap- 
proach of  fire  or  candle. f 

112.  Another  case  of  a  later  date,  in  which  the  sufferer  sur- 
vived the  accident  a  few  days,  is  recorded  in  a  German  journal. 
Don  G.  Maria  Bertholi,  a  friar  who  lived  at  Mount  Volere,  went 
to  the  fair  of  Filetto,  and  having  walked  about  all  day,  retired  in 
the  evening  to  the  house  of  a  relation  at  Fenille,  to  pass  the  night. 
Upon  his  arrival  he  went  directly  to  his  bed-room,  and  went  to 
bed,  having  a  handkerchief  placed  between  his  shoulders,  under 
his  shirt.     In  a  few  minutes  after  he  had  been  left  alone,  a  stifled 
noise,  mingled  with  cries,  was  heard  from  his  room  ;  and  when 
the  people  of  the  house  rushed  in,  they  found  him  on  the  floor, 
enveloped  in  a  lambent  flame.    He  was  visited  next  day  by  a  sur- 
geon, who  found  that  his  body  was  much  burned,  and  after  suf- 
fering a  good  deal,  he  died   on  the   fourth   day  after  the  acci- 
dent. 

113.  Such  are  some  of  the  most  remarkable  cases  of  the  occur- 
rence of  spontaneous  combustion  in  living  bodies,  which  have 
fallen  under  the  notice  of  competent   observers.      Among  the 
writers    who   have   expressly   treated  of  this    subject,  may   be 
mentioned  the  names  of  Lecat,  Kopp,  Vicq  D'Azyr,  Dr.  Thomas 
Trotter,  Dupuytren,  and  M.  Julia  Fontenelle,  the  last  mentioned 
of  whom,  in  a  paper  read  before  the  French  Academy,  a  few  years 
since,  draws  the  following  conclusions  from  a  review  of  the  evi- 
dence on  record  :  (1.)  Spontaneous  combustion  generally  happens 

How  did  the  case  related  by  Claromont  differ  from  others  already  stated  ? 
State  the  example  of  the  friar  Bertholi  ? 

«* 

*  Probably  cricket  or  tennis. 

t  Carol!  Claromontii,  D.  M.  Nob.  Lotharingi  de  Acre,  Locis  et  Aquis 
Terwe  Anglise.    Lond.  1672,  sm.  12mo.  pp.  21,  22. 


CAUSES  OF  SPONTANEOUS  COMBUSTION.  51 

to  those  who  are  accustomed  to  indulge  immoderately  in  the  use 
of  vinous  or  spirituous  liquors.  (2.)  Old  women  are  the  most  fre- 
quent victims  of  such  catastrophes.  (3.)  The  combustion  is 
sometimes  very  partial,  but  more  frequently  general;  and  the 
parts  which  most  commonly  escape  destruction  are  the  feet, 
hands,  and  upper  portion  of  the  head.  (4.)  This  kind  of  combus- 
tion often  does  not  extend  to  inflammable  substances  in  contact 
with  the  burning  body.  (5.)  Water,  instead  of  quenching  the 
fire,  adds  to  its  violence.  To  the  circumstances  thus  stated  as 
the  result  of  the  researches  of  M.  J.  Fontenelle,  it  may  be  added, 
that  in  most  of  the  cases  which  have  been  related,  the  combustion 
appears  to  have  commenced  when  the  subjects  of  it  were  in  bed. 

114.  As  to  the  causes  of  the  spontaneous  combustion  of  the 
human  body,  though  many  feasible  conjectures  might  be  advanced, 
the  phenomena  by  no  means  admit  of  complete  explanation.     It 
has  been  alleged,  that  the  intemperate  use  of  liquors  containing 
alcohol  may  cause  the  production  of  inflammable  gasses  within 
the  body,  and   that  the  solids  and  fluids  composing  it  may  also 
become  impregnated  with  undecomposed  spirit.     There  can  be  no 
doubt  that  sulphuretted  hydrogen  gas  is  frequently  formed  in  the 
intestinal  canal,  and  under  some  circumstances  other  inflammable 
compounds  of  hydrogen   may  be   accumulated   in   the   internal 
cavities  ;  spirits  when  swallowed  in  considerable  quantities  may 
possibly  be  interspersed  in  the  cellular  membrane;  and  though 
dram-drinkers  generally  become  emaciated,  and  their  foodies  are 
thus  deprived   of  the  adipose  or  fatty  matter  proper  to  healthy 
bodies,  yet  oleose,  and  therefore  inflammable  particles  must  still 
be  contained  in  some  of  the  fluids. 

115.  Hence  it  may   in  some  measure  be  conceived  how  the 
human  body  may  become  so  much  impregnated  with  combustible 
matter,  as  when  once  kindled,  to  be  partially  or  almost  wholly 
consumed,  without  the  addition  of  extraneous  fuel.      As  to  the 
immediate  or  exciting  cause  of  combustion  in  these  cases,  the  di- 
rect evidence  is  chiefly  negative.      In  most  instances,  it  has  been 
clearly  ascertained,  that  the  bodies  of  those  who  have  suffered 
have  not  been  set  on  fire  by  a  flame  or  flpark  from  any  previously 
'ignited  substance,  nor  by  the  lightning. 

116.  There  is,  however,  one  source  to  which  the  excitement  of 
thuse  alleged  spontaneous  combustions  may  with  probability  be 
attributed,  because  the  circumstances  are  favourable  to  its  pro- 
duction ;  and  that  is  the  electric  spark,  or  the  extrication  of  elec- 


Wliat  is  the  first  conclusion  drawn  by  Fontenelle  in  respect  to  spontane- 
ous combustions  ? 

What  class  of  persons  are  the  most  frequent  victims  of  this  calamity  ? 

What  parts  of  the  body  most  frequently  escape  combustion? 

What  appears  to  be  the  degree  of  coraj^wtibility  of  the  human  body  in 
such  instances  compared  with  that  of  otflppmaterials  ? 

What  i»  the  effect  of  water  in  cases  of  spontaneous  combustion  ? 

What  conjectures  have  been  formed  respecting  ita  cause  ? 

To  what  source  may  the  commencement  of  combustion  be  attributed  ? 


52  CHEMISTRY. 

tricity  possessing  such  a  degree  of  intensity  as  is  requisite  to  in- 
flame combustible  matter.  Several  instances  of  the  evolution  of 
electric  fire  from  animal  bodies,  when  excited  by  friction,  are 
mentioned  in  the  treatise  on  Electricity;*  and  others  in  which 
these  appearances  were  accompanied  with  actual  combustion,  are 
noticed  in  Sir  D.  Brewster's  Letters  on  Natural  Magic. f  To  what 
circumstances  the  production  of  electric  sparks,  that  could  set  fire 
to  inflammable  vapours,  should  be  ascribed,  in  any  given  case  of 
spontaneous  combustion,  can  only  be  conjectured  ;  but  as  most  of 
the  accidents  referred  to  occurred  to  persons  while  in  bed,  it  is  not 
impossible  that  the  electricity  might  be  excited  by  the  pressure  or 
friction  of  the  body  on  the  materials  of  the  bed.:J: 

117.  (5.)  This  very  important  law  of  chemical  affinity,  is  intimate- 
ly connected  with  the  second  law.    Though  chemical  combination 
takes  place  between  molecules  inconceivably  minute,  yet  their  , 
union  in  every  case  is  regulated  by  fixed  and  definite  proportions. 
As  to  the  nature  of  the  atoms  or  particles  of  the  respective  bodies 
with  which  we  are  acquainted,  we  know  nothing  certain..   For 
instance,  each  combining  molecule  of  oxygen,  of  hydrogen,  of 
carbon,  or  of  sulphur,  may  consist  of  several  component  particles 
or  sub-molecules  ;   for  there  is  nothing  inconsistent  in  supposing, 
that  though  matter  is  not  physically  capable  of  infinite  subdivison, 
yet  that  molecules  may  exist  far  more  attenuated  than  those  of  the 
most  simple  substance  which  has  hitherto  fallen  within  the  range 
of  our  observation. 

118.  The  development  of  the  principle  involved  in  this  law 
need  not,  however,  be  embarrassed  by  any  considerations  drawn 
from  the  questions  that  have  been  agitated  relative  to  the  divisi- 
bility of  matter ;  for  the  term  atom  here  is  not  to  be  taken  in  its 
strictest  accepUsjion,  (which  would  imply   indivisibility,)*    but 
merely  as  denoting  the  unit  of  combination,  or  the  proportional 
mass  or  quantity,  in  which  a  given  body  unites  with  other  bodies. 
It  may,  perhaps,  be  defined  to  be  the  smallest  quantity  to  which 
each  body  or  kind  of  matter  can  be  reduced,  without  loosing  its 
essential  properties  as  a  chemical  agent,  and  especially  that  pro- 
perty in  virtue  of  whicij§U  enters  into  combination  with   othet 
bodies. 

119.  The  relations   of  the  combining  propbrtions   or  atomic 

How  is  the  union  of  different  materials  regulated  in  regard  to  the  number 
of  atoms  ? 

Are  we  able  to  assign  the  absolute  nature  of  the  combining  particles  ? 
How  is  the  term  atom  as  employed  by  chemists  to  be  defined  ? 

*  See  Scientific  Class  Book,  pt.  i.  p.  446—7. 

t  See  Lett.  xiii.  pp.  321,  322. 

t  If  we  could  suppose  a  portion  of  the  phosphnms  combined  with  the 
body  to  be  extricated  in  connrffip  with  hydrogen,  the  combustion  would 
admit  of  a  ready  solution,  sincfl^Tiosphuretted  hydrogen  always  J^ikes  fire 
in  coming  to  the  air. 

§  From  the  Greek  "Aro^o,-,  indivisible  derived  from  the  priviflwe  a,  and 
•rifiv*,  to  cut. 


RELATIVE  WEIGHTS  OF  COMBINING  BODIES.  53 

quantities  of  different  substances  to  each  other,  may  be  considered 
with  respectjeither  to  weight  or  bulk.  Thus  8  parts  by  weight  of 
oxygen  will^Tfhite  with  1  part  of  hydrogen  to  form  water.  Sup- 
posing these  to  be  the  simplest  proportions  in  which  these  bodies 
combine,  the  atomic  weight  of  oxygen  will  be  8,  and  that  of 
hydrogen  1.  Again  nitrogen  will  unite  with  oxygen  in  the  follow- 
ing proportions : 
14  parts  by  weight  of  nitrogen  with  8  of  oxygen,  form  nitrous 

oxide. 
14  parts  by  weight  of  nitrogen  with  16  of  oxygen,  form  nitrous 

gas. 
14  parts  by  weight  of  nitrogen  with  24  of  oxygen,  form  hyponi- 

trous  acid. 
14  parts  by  weight  of  nitrogen  with  32  of  oxygen,  form  nitrous 

acid. 
14  parts  by  weight  of  nitrogen  with  40  of  oxygen,  form  nitric 

acid. 

So  that  the  lowest  proportion  in  which  oxygen  unites  with  nitro- 
gen, is  the  same  with  that  in  which  it  forms  water  with  hydrogen  y 
and  the  quantity,  by  weight,  in  which  nitrogen  unites  with  oxygen 
in  the  product,  (nitrous  oxide,)  is  as  14  to  8,  hence  the  former 
number  may  be  taken  as  the  atomic  weight  of  nitrogen.  Now  the 
other  numbers,  denoting  the  combining  weights  of  oxygen  with 
nitrogen,  are  all  multiples  in  various  proportions  of  its  atomic 
weight ;;  that  is,  nitrous  oxide  contains  1  atom  of  oxygen,  nitrous 
gas  2  atoms,  hyponitrous  acid  3  atoms,  nitrous  acid  4  atoms,  and 
nitric  acid  5  atoms,  each  atomic  quantity  being  combined  with  1 
atom  of  nitrogen. 

120.  In  the  same  manner  it  will  be  found  that  oxygen,  in  its 
combinations  with  carbon,  sulphur,  phosphorus,  the  metals,  and 
other  simple  bodies,  is  always  united  to  them  in  proportions 
relatively  equal  to  its  atomic  weight,  or  to  some  multiple  or  sub- 
multiple  of  that  weight.  The  following  are  the  atomic  weights, 
or,  as  they  are  sometimes  styled,  chemical  equivalents  of  the 
respective  bodies  enumerated : 

Hydrogen  .  .  1  ....  Carbon  ...  6 
Oxygen  .  .  8  ....  Phosphorus  .  12 
Nitrogen  ..  14  ....  Sulphur  .  .  16 
Sodium  ...  24  ....  Potassium  .  .  40 
Iron  ....  28  ....  Copper  ...  32 
Lead  .  .  -  .  104  ....  Mercury  .  .  200 

In  how  many  ways  may  the  relations  of  combining  proportions  be  con- 
sidered ?  Give  examples  of  the  combination  .by  weight. 

In  how  many  different  proportions  by  weight  may  nitrogen  and  oxygen 
combine  ? 

How  are  the  relations  of  oxygen  to~hydrogen  connected  with  those 
which  it  bears  to  nitrogen  ? 

What  constant  relation  is  found  to  exist  between  oxygen  and  the  sub- 
stances with  which  it  combines  ? 

What  is  the  body  whose  atomic  weight  is  taken  for  unity  ? 

E2 


54  CHEMISTRY. 

121.  If,  then,  we  trace  the  combinations  of  oxygen  with  either 
of  the  other  bodies  in  this  table,  it  will  appear  that  it  unites  in  the 
ratio  of  1  atom  of  oxygen  to  1  of  base,  1  to  2  of  base,  &c.     Thus 
carbon  combines  with   oxygen  in  two   proportions,  constituting 
two   distinct  compounds.     In  the  proportion  of    6   carbon   to  8 
oxygen,  it  unites  to  form  carbonic  oxide;  and  in  that  of  6  to  16 
oxygen,  it  forms  carbonic  acid.     Therefore  6  has  been  reckoned 
the  atomic  weight  of  carbon  ;    and  hence  it  will  follow  that  car- 
bonic oxide  is  a  compound  of  1  atom  of  each  of  its  constituents, 
and  that  carbonic  acid  consists  of  1  atom  of  carbon  with  2  of  oxy- 
gen.    Further,  with  sulphur,  oxygen  may  unite  in  three  propor- 
tions:   the   first,  or  hyposulphurous  acid,  composed  of  16  sul- 
phur-f-8  oxygen,  or  1  atom  of  each;    the  second,  or  sulphurous 
acid,  of  IG-p-lG,  or  1  atom  of  sulphur  to  2  of  oxygen  ;  and  the  third, 
or  sulphuric  acid,  of  16-J-24,  or  1  atom  of  sulphur  to  3  of  oxygen. 

122.  The  various  simple  bodies  not  only  combine  with  oxygen 
in  quantities  which  are  multiples  or  submultiples  of  their  atomic 
weights,  but  they  also  combine  in  the  same  manner  with  other 
bodies.     Hydrogen  forms  two  definite  compounds  with  sulphur. 
Sulphuretted  hydrogen  consists  of  1  hydrogen-f-16  sulphur,  or  1 
atom  of  each  body  ;  and  supersulphuretted  hydrogen  of  l-f-32,  or 
1  atom  of  hydrogen,  and  2  of  sulphur. 

123.  If,  however,  we  pursue  the  examination  of  the  relative 
combining  ratios  of  simple  bodies,  we  shall  find  some,  the  pro- 
portions of  whose  compounds  cannot  be  so  satisfactorily  deter- 
mined, as  those  last  mentioned.     In  the  first  place,  it  sometimes 
happens  that  the  only  known  combination  existing  between  two 
bodies  is  not  in  the  proportion  which  would  be  indicated  by  the 
numbers  representing  their  respective  chemical  equivalents.  Thus 
1  hydrogen  combines  with  8  oxygen,  and  the  latter  with  14  nitro- 
gen.    We  should  therefore  infer  that  the  quantity  of  hydrogen 
which  would  combine  with  14  of  nitrogen,  ought  to  be  1,  whereas 
it  is  3  ;  the  only  known  compound  of  the  latter  ingredients  being 
ammonia,  which  consists  of  14  by  weight  of  nitrogen  and  3  of 
hydrogen. 

124.  In  other  cases,  where  several  combinations  of  two  bodies 
occur,  the  ratio  between  the  numbers  is  not  as  1 — 2 — 3,  or  a  mul- 
tiple of  the  smallest,  but  as  1 — 1£ — 2,  or  some  other  intermediate 
quantity. 

What  is  the  relative  atomic  weight  of  sodium  ?  carbon  ?  sulphur  ?   cop- 
per ?  mercury  ? 

In  how  many  proportions  will  carbon  combine  with  oxygen  ? 


What  are  the  respective  compounds  called  ? 
Illustrate  the  principle  of  definii 


mite  proportions  as  between  sulphur  and 
hyd  rogen  ? 

"  What  is  the  first  exception  to  the  law  of  equivalents  in  chemical  com- 
position ? 

What  is  the  composition  of  ammonia  ? 
What  is  the  second  exception  ? 

How  far  may  these  exceptions  be  reconciled  with  the  general  theory  of 
definite  proportions? 


COMBINING  WEIGHTS  OF  BODIES.  55 

It  may  be  observed,  however,  tbat  in  these  cases,  the  very  ex- 
ception seems  to  prove  the  rule ;  for  with  regard  to  the  first  case, 
although  3  is  not  the  equivalent  of  hydrogen,  yet  it  is  a  multiple 
of  that  quantity ;  and  with  regard  to  the  second,  the  relation  of 
one-half  or  one-quarter  of  the  smaller  number  is  always  preserved 
in  the  other  combining  quantities,  so  that  it  is  plain  that  a  certain 
regularity  is  still  maintained  in  the  midst  of  these  apparent  ano- 
malies, and  that  the  combinations  take  place  even  here  agreeably 
to  some  fixed  and  settled  principle. 

125.  Many  of  these  exceptions,  indeed,  have  disappeared  in 
proportion  to  the  progress  of  discovery :  thus  a  few  years  ago  we 
were  acquainted  with  only  two  compounds  of  sulphur  and  oxy- 
gen, the  sulphurous  and  sulphuric  acids,  the  former  composed  of 
16  sulphur  and  16  oxygen,  the  latter  of  16  sulphur  and  24  oxy- 
gen, the  proportion  of  oxygen  in  the  two  compounds  being  there- 
fore as  2  to  3.     But  the  discovery  of  the  hyposulphurous  acid  has 
since  removed  this  anomaly,  by  presenting  us  with  a  compound  of 
16  sulphur  and  8  oxygen,  so  that  the  proportion  of  the  latter  is  to 
that  in  which  it  exists  in  the  second,  as  1  to  2.     It  is  probable, 
then,  that  in  many  cases  the  exception  is  only  apparent,  whilst  in 
others  it  seems  not  unlikely  that  two  equivalents  of  one  ingredient 
may  combine  respectively  with  two,  three,  and  four  equivalents 
of  the  other,  as  in  the  oxides  of  lead,  which,  according  to  Dr. 
Thomson,  consist  of 

Lead  104  X  2  =  208     .          .    Oxygen  8  X  2  =  16 

104  X  2  =  208  .     .     8  X  3  =.  24 

104  X  2  =  208     .     .     .     8X4  =  32* 

126.  It  will  be  perceived,  on  reference  to  the  preceding  esti- 
mates of  atomic  weights,  that  they  are  all    multiples   or  sub- 
multiples  of  the  atomic  weight  of  hydrogen,  that  being  unity. 
Hydrogen  being  the  lightest  of  all  the  bodies  with  which  we 
are  acquainted,  there  is  a  degree  of  convenience  in  making  its 
combining  weight  the  standard  from  which  those  of  others  are  to 
be  calculated.     It  must,  however,  be  understood,  that  the  com- 
bining weights  or  chemical  equivalents  have  no  reference  to  any 
real  standard  existing  in  nature,  but  that  they  merely  denote  the 
relative  quantities  in  which  different  substances  combine  together, 
and  it  is  immaterial  what  numbers  are  adopted  to  express  those 
quantities,  provided  the  entire  series  exhibits  the  same  proportions 
throughout.    Thus  ten  might  be  fixed  on  as  the  atomic  weight  of 

What  lias  the  progress  of  chemistry  developed  in  regard  to  these  excep- 
tions ? 

How  is  this  exemplified  in  the  compounds  of  oxygen  and  sulphur? 

What  is  the  atomic  weight  of  lead  ? 

How  many  compounds  does  it  form  with  oxygen  ? 

In  what  light  are  we  to  regard  the  weights  adopted  for  the  atoms  of  dif- 
ferent substances  ? 

*  Introduction  to  the  Atomic  Theory,  by  Charles  Daubeny,  M.  D.,  F.  R. 
S.,  Prof,  of  Chem.  at  Oxford.  1831,  8vo.  pp.  42,  43. 


50  CHEMISTRY. 

hydrogen,  in  which  case  that  of  carbon  would  be  60,  that  of  oxy- 
gen 80,  that  of  sulphur  160,  that  of  iron  280,  and  so  on,  all  being 
augmented  in  tenfold  proportion.  The  combining  number  of 
hydrogen  might  be  reckoned  100  or  1000,  and  those  of  the  others 
increased  in  the  same  ratio  ;  or  any  given  number  whatever  might 
be  selected  instead  of  unity,  and  a  scale  of  combining  quantities 
formed  to  correspond  with  it. 

127.  But  the  obvious  advantages  of  taking  a  series  commencing 
with  unity  must  at  once  be  perceived.     All  chemists,  however, 
are  not  agreed  as  to  the  propriety  of  making  the  atom  of  hydro- 
gen the  foundation  of  the  scale  of  equivalents.     Thus  Dr.  Thom- 
son reckons  the  atomic  weight  of  oxygen  as  1,  and  consequently 
that  of  hydrogen  g  or  0.125,  that  of  carbon  |-  or  0.75,  and  that 
of  sulphur  V6  °r  2 ;  and  alters  the  series  throughout  in  the  same 
ratio.     Others  have  fixed  on  10  or  100  as  the  combining  number 
°'  oxygen?  ana<  regulated  their  scales  accordingly. 

128.  The  preceding  observations  will  enable  the  reader  to  un- 
derstand in  some  degree  the  causes  of  the  varieties  of  the  atomic 
weights  attributed  by  different  writers  to  the  same  body ;  some 
estimating  the  weight  with  reference  to  that  of  hydrogen  as  the 
standard,  and  some  with  reference  to  oxygen.    There  is,  however, 
another  source  of  discrepancy,  which  must  not  be  left  unnoticed. 
The  determination  of  the  atomic  weights  of  bodies  must  in  the 
first  instance  depend  on  chemical  analysis  :  and,  as  Professor 
Daubeny  observes,  "we  must  admit  that  it  is  doubtful  whether 
such  accuracy  in  chemical  analysis  has  yet  been  attained,  as  to 
enable  us  to  answer  positively  for  a  fraction  not  exceeding  the 
300th  or  400th  part  of  the  whole  quantity  to  be  determined ; 
and  this  degree  of  exactness  at  least  would  have  been  required 
to  verify  the  law  satisfactorily  in  the  higher  part  of  the  scale."* 
Hence  it  is  that  Ber/elius,  estimating  the  atomic  weights  of  dif- 
ferent bodies  with  reference  to  hydrogen,  has  given  numbers  vary- 
ing more  or  less  from  those  which  have  been  generally  adopted  ; 
his  numbers  being  founded  on  his  own  analyses.  The  well-known 
skill  and  talent  for  research  of  this  celebrated  chemist,  afford 
strong  presumptions  in  favour  of  the  accuracy  of  his  conclusions, 
which  have  been  generally  confirmed  by  more  recent  experiments 
of  Dr.  Turner,  Professor  of  Chemistry  in  the  University  of  Lon- 
don.    This  gentleman  states,  as  the  result  of  his  investigations, 
that,  without  denying  the  possibility  of  hereafter  tracing  some 

What  is  the  practice  of  different  chemists  in  regard  to  the  substance 
whose  atomic  weight  is  made  unity  ? 

What  will  be  the  relative  number  for  hydrogen  when  the  weight  of  the 
atom  of  oxygen  is  made  1  ? 

What  will  that  of  sulphur  then  be? 

On  what  does  the  determination  of  atomic  weights  depend  ? 

To  what  degree  of  exactness  must  analysis  be  carried  in  order  to  verify 
the  numbers  expressing  atomic  weights  ? 

*  Introd.  to  the  Atomic  Theory,  p.  39. 


SCALE  OF  CHEMICAL  EQUIVALENTS.  57 

simple  relation  between  the  equivalents  of  bodies,  he  is  convinced 
that  the  hypothesis  of  all  equivalents  being  multiples  by  a  whole 
number  of  the  equivalent  of  hydrogen,  is  inconsistent  with  the 
best  analyses  which  chemists  at  present  possess."* 

129.  The  best  tables  or  scales  of  chemical  equivalents,  there- 
fore, which  have  been  hitherto  produced,  are  to  be  considered  as 
by  no  means  perfect,  nor  in  the  present  state  of  our  knowledge 
capable  of  being  rendered  so; '.but  notwithstanding  their  admitted 
defects,  they  may  be  provisionally  adopted,  as  affording  facilities 
for  making  calculations  of  the  contents  of  compound  bodies,  or 
for  checking  the  results  of  experiment,  by  reference  to  the  com- 
bining proportions  of  bodies  which  have  been  submitted  to  analysis. 

130.  A  most  ingenious  and  useful  modification  of  the  system 
of  atomic  weights  was  contrived  by  Dr.  Wollaston,  constituting 
his  Logometric  Scale  of  Chemical  Equivalents.     It  is  similar  in 
principle  to  the  common  sliding  rule,  and  like  that  instrument,  has 
the  usual  Gunter's  line,  or  scale  of  logometric  numbers,  on  the 
slider ;  and  upon  a  line  adjacent  to  the  slider,  are  marked  certain 
points,  corresponding  to  the  numbers  that  represent  the  combining 
weights  of  the  various  elementary  bodies,  and  of  the  acids,  alka- 
lies, and  other  chemical  compounds.     Thus  it  is  so  constructed 
that  when  the  number  10,  which  is  reckoned  the  atomic  weight 
of  oxygen,  stands  opposite  to  the  name  of  that  body,  hydrogen 
will  stand  opposite  1.25,  carbon  opposite  715,  nitrogen  opposite 
17.5,  iron  opposite  35.0,  and  sulphur  opposite  to  20.     Hence,  if 
we  wish  to  know  how  much  of  either  of  these  bodies,  as,  for  in- 
stance, iron,  will  form  a  binary  combination  with  a  given  quantity 
of  oxygen,  as  14.5,  we  bring  that  number  on  the  slider  opposite 
the  word  oxygen  in  the  scale,  and  the  number  50  will  stand  oppo- 
site the  word  iron  ;  indicating  that  50  parts  by  weight  of  iron  will 
combine  with  14J  of  oxygen  to  form  protoxide  of  iron.     And  in 
the  same  manner  it  will  be  seen  how  much  of  any  other  body 
will  combine  with  any  given  quantity  of  oxygen. f 

/  131.  j  As  the  combining  atoms  of  bodies  bear  certain  relations 
to  eacrh  other  by  weight,  so  likewise,  in  some  states  they  may 
manifest  corresponding  relations  as  to  bulk  or  volume.)  Not  long 
after  Mr.  Dalton  in  England  had  directed  the  attention  of  chemists 
to  the  relation  existing  between  the  weights  of  bodies  which  com- 
bine in  different  proportions,  MM.^Qjay  Lussac  and  Humboldt  in 
France  established  a  similar  correspondence  between  the  volumes 
of  oxygen  and  hydrogen,  which  unite  together,  proving  that  they 

What  is  the  result  of  Professor  Turner's  investigation  on  this  subject? 
How  far  may  the  scales  of  equivalents  in  use  among  chemists  be  relied  on? 
What  is  the  description  of  Wollaston's  scale  of  equivalents  ? 
Describe  some  applications  of  that  scale. 

In  what  other  respect  besides  that  of  weight  are  combining  bodies  found 
related  to  each  other  ? 

*  Second  Report  of  the  British  Association,  1832,  p.  572. 
t  See  Paper  on  a  Synoptic  Scale  of  Chemical  Equivalents,  by  Dr.  Wol- 
lasion,  in  Philos.  Trans,  for  1814. 


58  CHEMISTRY. 

combined  in  the  proportion  of  one  volume  of  the  first  to  two  of 
the  second.1  Shortly  after  the  French  philosophers  extended  the 
same  inference  generally  to  the  combinations  between  gases ; 
showing  that  they  united  in  the  exact  proportions  of  1  volume  of 
the  one,  to  1,  2,  3,  or  some  other  whole  number  of  volumes  of  the 
second. 

132.  Thus  one  volume  of  carbonic  acid,  and  one  volume  of  am- 
monia, form  carbonate  of  ammonia  ;  one  of  nitrogen  and  three 
of  hydrogen  form  ammonia;  one  of  chlorine  and  one  of  hydrogen 
form  muriatic  acid.\  The  same  law  applies  to  vapours,  such  as 
those  of  alcohol  and  ether,  as  well  as  to  true  gases.  \M .  Gay 
Lussac  even  rendered  it  probable  that  the  combinations  between 
solids  and  gases  follow  the  same  principle :  that  quantity  of  the 
former  uniting  with  one  or  more  volumes  of  the  latter,  which,  if 
existing  in  the  form  of  vapour,  would  have  occupied  a  correspon- 
dent bulk.  Thus  carbon  6  and  oxygen  16,  by  weight,  form  car- 
bonic acid  ;  hence  100  cubic  inches  of  oxygen  will  combine  with 
12.7  grains  of  carbon.  For  100  cubic  inches  of  oxygen  weigh 
33.8888  grains,  and,  as  16  :  6  : :  33.8888  :  12.7.  Now  12.7  grains 
of  carbon  may  be  shown  to  occupy  when  in  vapour  100  cubic 
inches,  or  exactly  the  same  space  as  33.8888  grains  of  oxygen,  so 
that  the  combining  quantities  of  the  two  bodies  correspond  in 
volume  no  less  than  in  the  number  of  atoms  of  which  a  volume 
of  each  is  made  up. 

133.  "  When  aeriform  fluids  combine  together,  and  produce  by 
their  union  a  new  gas,  they  generally  contract  in  bulk,  or  occupy 
less  space  than  they  did  when  separate.  \^_Now  M.  Gay  Lussac 
found  that  when  this  takes  place,  they  contract  either  to  one-half, 
one-quarter,  one-third,  two-thirds,  or  some  other  quantity  bearing 
an   exact  proportion   to   their  antecedent  bulk.     Thus  carbonic 
oxide  2  volumes,  with  oxygen  1  volume,  form  together  2  volumes 
of  carbonic  acui  gas,  there  being  a  contraction  of  one-third  ;  3 
volumes  of  hydrogen  and  1  of  nitrogen,  form  2  volumes  of  ammonia, 
the  gases  contracting  to  one-half,  and  so  with  the  rest."* 

134.  These  facts  exhibit  the  doctrine  of  combining  quantities  in 

On  what  researches  was  the  theory  of  volumes  founded  ? 

What  is  the  relation  of  the  two  gaseous  ingredients  of  water  in  regard 
to  their  bulk  before  combination  ? 

What  number  of  volumes  of  the  two  constituents  enter  in  to  combination 
to  form  carbonate  of  ammonia  ? 

How  has  Gay  Lussac  extended  the  theory  of  volumes  to  other  than  ga- 
seous bodies  ? 

How  may  we  compute  the  weight  of  carbon  in  a  given  bulk  of  carbonic 
acid  ? 

What  generally  happens  in  respect  to  the  bulk  of  combining  gases  after 
their  union  ? 

Illustrate  this  in  the  case  of  carbonic  oxide  and  oxygen  ; — hydrogen  and 
nitrogen. 

*  Daubeny's  Introd  to  the  Atomic  Theory,  pp.  45,  46. 


ATOMIC  CONSTITUTION  OF   BODIES.  59 

a  new  point  of  view,  and  serve  to  corroborate  the  inferences  con- 
cerning the  atomic  constitution  of  bodies  drawn  from  the  consi- 
deration of  the  relations  that  have  been  shown  to  subsist  between 
the  weights  of  chemical  equivalents.  When  we  attempt,  however, 
to  reconcile  the  principle  of  combining  weights  with  that  of  com- 
bining volumes,  difficulties  occur  which  can  only  be  completely 
dissipated  by  future  researches.  Thus  we  find  that  100  cubic 
inches  of  oxygen  gas  will  combine  with  200  cubic  inches  of 
hydrogen,  to  form  200  cubic  inches  of  aqueous  vapour ;  so  that  the 
quantity  of  the  hydrogen  in  water  by  measure,  is  double  that  of  the 
oxygen.  Hence  Sir  H.  Davy  concluded  that  an  atom  of  water 
consisted  of  2  atoms  of  hydrogen  and  1  of  oxygen ;  and  therefore 
that  the  atom  of  the  latter  should  be  represented  by  16,  that  of  the 
former  being  unity. 

135.  This  estimate  of  the  weight  of  an  atom  of  hydrogen  as 
being  y?  that  of  an  atom  of  oxygen  is  inconsistent  with  the  combin- 
ing proportions  of  the  hydrogen  in  other  cases,  and  it  has  conse- 
quently been  rejected,  while  that  originally  proposed  by  Dr.  Dai- 
ton,  which  rates  the  two  volumes  of  hydrogen  as  one  atom,  has 
been  preferred  in  making  computations.  Dr.  Prout,  however,  is 
disposed  to  adhere  rigorously  to  the  principle  of  equivalent  vo- 
lumes rather  than  that  of  combining  weights.  He  says  :  "  It  has 
been  found  by  experiment,  that  the  same  volumes  of  different 
bodies  in  the  gaseous  states  have  very  different  weights.  Thus, 
for  instance,  a  volume  of  oxygen  weighs  sixteen  times  as  much 
as  the  same  volume  of  hydrogen.  Hence,  as  the  number  of  self- 
repulsive  molecules  in  each  of  these  gases  is'  presumed  to  be  the 
same,*  the  weight  of  the  self-repulsive  molecule  of  oxygen  must, 
of  course,  be  sixteen  times  greater  than  that  of  hydrogen ;  and 
generally,  the  weights  of  the  self-repulsive  molecules  of  all  bodies, 
will  be  as  the  specific  gravities  of  these  bodies  in  the  gaseous 

What  effect  has  the  theory  of  volumes  on  that  of  atomic  weights  ? 
What  difficulties  occur  in  reconciling  the  two  ? 
What  view  has  Dr.  Prout  advanced  on  this  subject? 
On  what  is  the  presumption  that  equal  volumes  of  all  gases  contain  the 
same  number  of  atoms  ?  [See  note.] 

*  The  presumption  that  equal  volumes  of  different  gases  contain  exactly 
the  same  number  of  atoms,  is  founded  chiefly  on  a  law  propounded  by 
Mariotte,  that  the  volume  of  any  gas  is  universally  as  the  pressure  applied 
to  it;  since  it  is  supposed  that  if  the  number  of  atoms  in  each  gas  was  not 
the  same,  the  law  of  diminution  of  volume  under  pressure  would  vary  with 
respect  to  the  different  gases.  It  appears,  however,  from  the  most  exact 
experiments,  that  this  law  strictly  applies  only  to  the  permanent  gases,  as 
oxygen,  hydrogen,  and  nitrogen,  which  cannot  be  reduced  to  the  liquid 
state  by  extreme  pressure  and  low  temperature ;  and  these  gases  at  any 
given  temperature  diminish  in  volume  under  pressure  in  the  same  ratio 
with  atmospheric  air.  But  sulphurous  acid  and  other  condensable  gases, 
submit  to  pressure  more  readily  than  common  air.  V.  Mitscherlich's  In- 
troduction to  Chemistry,  vol.  i.  p.  131  ;  and  Johnston's  Report  on  Chem. 
Science  to  the  British  Association,  1832,  pp.  420,  421.  451.  Hence  it  must 
be  admitted,  that  Mariotte's  law,  while  it  fails  with  respect  to  condensable 
gases  or  vapours,  at  least  holds  good  with  regard  to  oxygen  and  hydrogen. 


60 


CHEMISTRY. 


state,  or  will  bear  certain  simple  relations  to  these  specific  gravi- 
ties."* He  subsequently  remarks,  that  "  a  strictly  philosophical 
arrangement,  supposing  the  principles  we  have  advanced  to  be 
well  founded,  would,  require  that  the  volume  in  all  instances  should 
be  made  the  molecular  unit ;  in  which  case  the  relative  weights  of 
the  self-repulsive  molecules  of  hydrogen  and  oxygen,  as  above 
mentioned,  will  be  as  1  to  16. "f 

136.  From  the  doctrine  of  relations  between  combining  atoms 
or  self-repulsive  molecules  and  combining  volumes  adopted  by 
Dr.  Prout,  it  will  directly  follow,  as  he  observes,  that  the  atoms 
of  bodies   will  be  as   their   specific   gravities,  or   have  certain 
relations  to  their  specific    gravities.     Hence   the   determination 
of  the   exact  specific   gravities   of  the  gases  is  of  the   utmost 
importance.    Unfortunately,  in  the  results  hitherto  obtained  from 
their   experiments  and  calculations,  chemists  agree  as  little  in 
their  estimates  of  specific  gravities,  as  in  those  of  atomic  weights. 
Till  these  can  be  ultimately  determined  through  the  continued 
researches  of  philosophical  inquirers,  we  must  employ  the  most 
accurate  approximations  which  can  be  deduced  from  the  informa- 
tion already  obtained. 

137.  In  this  point  of  view  the  following  table  of  the  specific 
gravities  of  aeriel  bodies,^:  from  Brande's  Journal  of  Science,  vol. 
lii.,  is  deserving  of  attention.     It  was   drawn   up  by  Professor 
Meinecke,  of  Halle,  in  Saxony,  from  stoechiometric§  calculations, 
founded  on  the  comparison  of  the  experiments  of  various  chemists 
on  the  different  elastic  fluids. 

What  consequence  will  follow  from  admitting  this  supposition  ? 
What  conformity  exists  among  the  several  determinations  of  the  specific 
gravity  of  the  gases  as  obtained  by  different  chemists  ? 

*  Dr.  Prout's  Chemistry,  Meteorology,  &c.,  p.  134.    t  Id.  p.  135. 

\  In  the  table  of  the  text  the  specific  gravity  of  each  vapour  is  compared 
with  that  of  common  air,  taken  at  the  temperature  of  the  boiling  point  of 
the  liquid  from  which  it  arose.  The  following  table  exhibits  the  specific 
gravity  compared  with  air,  at  60°,  and  also  that  of  each  liquid,  at  60°  together 
with  its  boiling  point : — 


§.* 

it 

I 

| 

Kame  of  the  Vapour. 

$rl 

6° 

V? 

f 

£°a 

£'a 

«§• 

1 

Vapour  of  water. 
Do.      hydrocyanic  acid 
Do.      alcohol          .        . 

.947 
1.603 

.481 
.912 
1.311 

1.000 
.7039 

.798 

212° 
79.7 
173 

Do.      muriatic  ether 

2.219 

2.255 

.874 

52 

Do.      sulphuric  acid 
Do.      sulphuret  of  carbon 
Do.      oil  of  turpentine 
Do.      hvdriodic  ether 

2.580 
2.638 
5.013 
5.475 

2.415    .632 
2.376  1.272 
3.3431  .792 
4.666'  1.921 

96 
116 
326 
148 

See  Thompson  on  Heat,  p.  218—  Ed. 

§That  is,  calculations  of  the  specific  gravi 
ledge  of  that  of  their  elements.    From  Sroi 


ty  of  compounds  from  a  know- 
etoy an  element,  and 


SPECIFIC  GRAVITIES  OF  AERIAL  BODIES.  61 

Table  of  the  Specific  Gravities  of  Gases  and  Vapours. 


^    ' 

2 

II 

&S 

|3 

<! 

il 

£ 

*£ 

1.  Hydrogen  gas 

0.0694 

i 

0.0625 

2.  Protocarburetted  hydrogen  gas 

0.5555 

8 

0.5 

3.  Azoted  hydrogen  gas,  or  ammonia 

0.5901 

8| 

0.5312 

4.  Vapour  of  the  protoxide  of  hydrogen,  or  aqueous 

0.6250 

9 

0.5625 

vapour          ..... 

5.  Vapour  of  hydrocyanic  acid,  or  prussic  acid 
6.  Gaseous  protoxide  of  carbon,  or  carbonic  oxide 

0.9374 
0.9722 

!? 

0.8437 
0.875 

7.  Percarburetted  hydrogen  gas,  or  olefiant  gas 

0.9722 

14 

0.875 

8.  Azote,  or  nitrogen  gas 

0.9722 

14 

0.875 

9.  Atmospheric  air                          .            .                       jl. 

14§ 

0.9 

10.  Gaseous  deutoxide  of  azote,  or  nitrous  gas 

1.041 

15 

0.937 

11.  Oxygen  gas           ..... 
12.  Hydrosulphuric  gas,  or  sulphuretted  hydrogen 

1.111 
1.150 

16 
17 

1. 
1.062 

13.  Hydrochloric  gas,  or  muriatic  acid  gas             .           ,1.274 
14.  Carbonic  acid  gas         ....               1.527 

181 
22" 

1.156 
1.375 

15.  Gaseous  protoxide  of  azote,  or  nitrous  oxide             |1.527 

22 

1.375 

16.  Alcoholic  vapour                         .             .            .           11.597 

23 

1.437 

17.  Vapour  of  cyanogen 

1.806 

26 

1.625 

18.  Chlorocyanic  acid  vapour 

2.153 

31 

1.937 

19.  Sulphurous  acid  gas               .             .            .                  2.222 

32 

2. 

20.  Chlorine               .                         ...            2.5 

33    2.25 

21.  Ethereal  vapour        ....                 2.569 

37    2.312 

22.  Nitrous  acid  vapour 

2.638 

38    2.375 

23.  Percarburet  of  sulphur,  or  sulphuret  of  carbon 

2.638 

38    2.375 

24.  Carbochlorir,  acid,  or  phosgene  gas 

3.473 

50    3.125 

138.  (6.)  The  object  of  this  law  of  chemical  affinity  is  to 
determine  the  influence  of  circumstances  on  the  combination 
of  bodies  with  each  other.  [1.]  With  respect  to  those  cases 
where  compounds  are  formed  from  the  mere  mixture  of  their  con- 
stituent parts,  but  few  observations  will  be  requisite.  Some 
bodies  exert  no  action  on  each  other,  when  placed  in  contact 
under  any  given  conditions ;  and,  therefore,  so  far  as  our  knowledge 
extends,  are  to  be  considered  as  incapable  of  union.  The  simple 
bodies  in  general  have  a  strong  tendency  to  combine  together ; 
but  when  two  compound  bodies  are  intermixed,  it  will  frequently 
happen  that  instead  of  forming  a  mingled  mass  or  a  single  che- 
mical compound,  they  will  decompose  each  other.  Among  the 
circumstances  that  facilitate  the  union  of  bodies,  are  intermixture 

How  many  times  is  atmospheric  air  heavier  than  hydrogen  ? 

How  many  times  is  sulphurous  acid  gas  heavier  than  oxygen? 

How  many  times  is  chlorine  heavier  than  atmospheric  air  ? — than  hydro- 
gen ? — than  oxygen  ? 

What  is  the  heaviest  of  gaseous  bodies  ? 

Is  the  vapour  of  ether  or  of  alcohol  the  heavier  ? 

What  tendency  is  manifested  by  the  simple  bodies  in  regard  to  each 
other  ? 

What  circumstances  facilitate  the  union  of  bodies  ? 
F 


62  CHEMISTRY. 

and  augmentation  of  temperature,  the  effects  of  which  have  been 
noticed  in  treating  of  the  second  and  third  laws  of  affinity. 

139.  [2.]  In  the  case  of  single  elective  attraction,  exhibited 
in  the  decomposition  of  a  compound  body  when  a  simple  body  is 
presented  to  it,  the  phenomena  will  depend  on  the  relative  affinity 
of  the  latter  for  one  of  the  elements  of  the  former.     The  series 
of  decompositions  adduced  to  exemplify  the  first  law  of  chemical 
affinity  may  be  referred  to  as  exhibiting  to  a  certain  extent  the 
relative  affinities  of  the  several  bodies.     The  law  of  elective  at- 
traction on  which  such  decompositions  depend,  is,  however,  sub- 
iect  to  some  important  modifications.    It  has  been  stated  that  lime 
separates  ammonia  from  its  combination  with  sulphuric  acid.  (See 
p.  29.)     "  Bergmann  conceived  that  such  decompositions  were 
solely  determined  by  chemical  attraction,  and  that,  consequently, 
the  order  of  decomposition  represented  the  comparative  forces  of 
affinity  :  and  this  view,  from  the  simple  and  natural  explanation 
it  afforded  of  the  phenomenon,  was  for  a  time  very  generally 
adopted. 

140.  But  Bergmann  was  in  error.     It  does  not  necessarily  fol- 
low, because  lime  can  separate  ammonia  from  sulphuric  acid,  that 
the  lime  has  a  greater  attraction  for  the  acid  than  the  volatile  al- 
kali.    Other  causes  are  in  operation  which  modify  the  action  of 
affinity  to  such  a  degree  that  it  is  impossible  to  discover  how 
much  of  the  effect  is  owing  to  that  power.     It  is  conceivable  that 
the  ammonia  may  in  reality  have  a  stronger  attraction  for  sul- 
phuric acid  than  lime,  and  yet  the  lime,  from  the  great  influence 
of  disturbing  causes,  might  succeed  in  decomposing  sulphate  of 
ammonia.     The  justness  of  the  foregoing  remark  will  be  made 
obvious  by  the  following  example  :  When  a  stream  of  hydrogen 
gas  is  passed  over  the  oxide  of  iron  heated  to  redness,  it  deprives 
the  iron  of  its  oxygen  entirely,  combining  with  it  so  as  to  form 
water.    On  the  contrary,  when  watery  vapour  is  brought  into  con- 
tact with  red-hot  metallic  iron,  the  oxygen  of  the  water  quits  the 
hydrogen,  and  combines  with  the  iron. 

141.  It  follows,  from  the  result  of  the  first  experiment,  according 
to  Bergmann,  that  hydrogen  has  a  stronger  attraction  for  oxygen 
than  iron  has  ;  and  from  the  second,  that  iron  has  a  greater  affinity 
for  oxygen  than  hydrogen  has.     But  these  inferences  are  incom- 
patible with  each  other.     The  affinity  of  hydrogen  for  oxygen 
must  be  either  equal  to  that  of  iron,  or  greater,  or  less.     If  the  first 
is  the  case,  then  the  result  of  both  experiments  was  determined 
by  modifying  circumstances ;   since  neither  of  those  substances 

On  what  do  the  phenomena  of  single  elective  attraction  depend  ? 

What  view  of  Bergmann's  on  this  subject  was  formerly  adopted  by  che- 
mists ? 

What  example  furnishes  an  exception  to  the  law  that  chemical  decom- 
position depends  entirely  on  affinity  ? 

How  may  we  reason  on  the  experiment  with  hydrogen,  watery  vapour, 
and  hot  iron  ? 


SIMPLE  ELECTIVE  ATTRACTION.  63 

ought,  on  this  supposition,  to  take  oxygen  from  the  other.  If  the 
second,  then  the  decomposition,  in  one  of  the  experiments,  must 
have  been  determined  by  extraneous  causes,  in  direct  opposition  to 
the  tendency  of  affinity."* 

142.  The  fallacy  of  Bergmann's  inferences  relative  to  the  absolute 
effect  of  affinity  in  the  production  of  chemical  decompositions  was 
first  pointed  out  by  Berthollet,  who  demonstrated  that  tables  of 
decomposition  cannot  be  considered  as  indicating,  under  all  cir- 
cumstances, the  order  of  affinity  of  bodies.  He  also  showed,  that 
the  action  of  affinity  is  modified  by  various  causes,  of  the  operation 
of  which  in  a  variety  of  cases  he  gave  a  consistent  explanation. 
That  philosopher,  however,  overrated  the  influence  of  occasional 
causes  on  the  phenomena  of  decomposition,  when  he  attributed 
them  to  such  causes  only,  denying  the  existence  of  elective  affinity 
as  an  invariable  force.  Dr.  Turner  observes  :  "  That  chemical  at- 
traction is  exerted  between  bodies  with  different  degrees  of  energy 
is  indisputable.  Water  has  a  much  greater  affinity  for  muriatic 
acid  and  ammoniacal  gases  than  for  carbonic  acid  and  sulphuret- 
ted hydrogen,  and  for  these  than  for  oxygen  and  hydrogen.  The 
attraction  of  lead  for  oxygen  is  greater  than  that  of  silver  for  the 
same  substance.  The  disposition  of  gold  and  silver  to  combine 
with  mercury  is  greater  than  the  attraction  of  platinum  and  iron 
for  that  fluid.  As  these  differences  cannot  be  accounted  for  by 
the  operation  of  any  modifying  causes,  we  must  admit  a  difference 
in  the  force  of  affinity  in  producing  combination.  It  is  equally 
clear,  that  in  some  instances  the  separation  of  bodies  from  one 
another  can  only  be  explained  on  the  same  principle.  No  one,  I 
conceive,  will  contend  that  the  decomposition  of  hydriodic  acid  by 
chlorine,  or  of  sulphuretted  hydrogen  by  iodine,  is  determined  by 
the  concurrence  of  any  modifying  circumstances."! 

143.  [3.]  Complex  elective  attraction  differs  from  that  already 
described,  in  exhibiting  a  more  complicated  play  of  affinities;  and 
hence  it  is  in  such  cases  that  anomalous  appearances  occur,  from 
the  influence  of  disturbing  causes.  Compounds  may  be  decom- 
posed by  means  of  complex  affinity,  when  they  resist  the  opera- 
tion of  simple  affinity.  Thus  nitric  acid  alone  will  not  decompose 
sulphate  of  soda,  for  the  sulphuric  acid  combined  with  the  soda 
has  a  stronger  affinity  for  that  alkali  than  the  nitric  acid ;  but  if  a 
solution  of  nitrate  of  barytes,  or  the  compound  of  nitric  acid  with 
the  earth  called  barytes,  be  added  to  a  solution  of  sulphate  of  soda, 
a  double  decomposition  will  take  place,  the  sulphuric  acid  quitting 

What  did  Berthollet  attempt  to  prove  in  regard  to  the  relation  between 
affinity  and  chemical  composition? 

By  what  examples  may  we  prove  that  different  degrees  of  energy  are  ac- 
tually exerted  between  different  bodies? 

What  cases  of  decomposition  may  be  cited  to  prove  the  same  point? 

In  what  respect  does  complex  differ  from  simple  elective  attraction  ? 

State  an  example  of  decomposition  by  complex  elective  attraction? 

*  Dr.  Turner's  Elements  of  Chemistry,  4th  ed.  1833,  pp.  167,  168. 
t  Ibid. 


64  CHEMISTRY. 

the  soda  to  unite  with  the  barytes,  and  the  nitric  acid  separating 
from  the  earth  to  combine  with  the  alkali ;  and  the  result  will  be 
two  new  compounds,  namely,  sulphate  of  barytes  and  nitrate  of 
soda. 

144.  Such  processes  of  complex  affinity  may  be  conveniently 
exhibited  by  means  of  a  diagram,  which  appears  to  have  been  first 
employed  by  Dr.  Black.  The  result  of  the  decompositions  just 
described  might  be  thus  represented  : 

Nitric  Acid Barytes 


Sulphuric  Acid Soda 

145.  In  any  given  case,  the  relative  affinities  of  the  substances 
for  each  other  may  be  denoted  by  numbers.     When  two  salts  are 
brought  within  the  sphere  of  mutual  action,  they  will  not  become 
decomposed,  unless  the  affinities  which  tend  to  form  new  com- 
pounds are  superior  to  those  which  tend  to  keep  the  constituents 
of  the  original  compounds  united.     Mr.  Kirwan  adopted  the  term 
divellent  affinity,  to  signify  that  attraction  which  favours  decompo- 
sition; and  quiescent  affinity  for  that  which  opposes  a  change  of 
state. 

146.  The  effect  of  peculiar  circumstances  on  complex  affinity 
may  be  observed  when  carbonate  of  lime  is  mixed  with  muriate 
of  ammonia,  and  the  two  salts  in  a  dry  state  are  exposed  to  heat; 
double  decomposition  takes  place,  and  carbonate  of  ammonia  and 
muriate  of  lime  are  produced  :  and,  on  the  contrary,  if  a  solution 
of  carbonate  of  ammonia  in  water  be  mixed  with  a  solution  of 
muriate  of  lime,  decomposition  will  also  take  place,  the  lime  will 
unite  with  the  carbonic  acid,  and  the  ammonia  will  enter  into  com- 
bination with  muriatic  acid.     The  decomposition  which  occurs  in 
this  case,  however,  is  more  extensive  than  might  at  first  be  sus- 
pected.    What  is  called  muriate  of  lime  is  really  a  chloride  of 
calcium,  or  the  metal  which  forms  the  basis  of  lime.     Now,  when 

Draw  and  explain  the  diagram  illustrative  of  this  decomposition  ? 

When  may  two  salts  actually  decompose  each  other  ? 

How  may  their  relative  affinities  be  expressed  ? 

What  terms  did  Kirwan  employ  to  express  the  forces  which  favour  and 
those  which  prevent  decomposition  ? 

In  what  example  may  we  find  the  effect  of  modifying  circumstances  on 
chemical  affinity  ? 

How  is  the  anomaly  in  this  case  to  be  explained  ?  , 


COMPLEX  ELECTIVE  ATTRACTION.  65 

carbonate  of  lime  and  muriate  of  ammonia  are  heated  tog-ether, 
both  the  lime  and  muriatic  acid  are  decomposed,  the  oxygen  of 
the  lime  and  the  hydrogen  of  the  acid  being  driven  off;  while  the 
metallic  calcium  enters  into  union  with  the  chlorine  from  the 
muriatic  acid,  and  the  carbonic  acid  which  was  united  with  the 
lime  combines  with  the  ammonia.  The  decomposition  of  the  car- 
bonate of  ammonia  and  chloride  of  calcium,  by  mixing  their  solu- 
tions, maybe  similarly  explained  ;  for  the  chloride  of  calcium  de- 
composes water,  the  oxygen  of  which  combines  with  the  metal  to 
form  lime,  and  the  hydrogen  unites  with  the  chlorine  thus  set  free 
to  form  muriatic  acid,  which  separates  the  carbonic  acid  from  the 
ammonia  to  combine  with  it,  leaving  the  latter  acid  to  form  a  union 
with  the  lime. 

147.  Another   case  of  reciprocal  decomposition  may  here  be 
mentioned,  which  does  not  so  readily  admit  of  explanation.     Sir 
H.  Davy  has  remarked,  that  "  in  many  cases,  decompositions  that 
cannot  be  produced  by  single  attractions,  may  be  produced   by 
double  affinities.     Thus  the  elements  of  sulphate  of  barytes,  or 
the  combination  of  sulphuric  acid  with  the  earth  called   barytes, 
are  so  firmly  united,  that  no  alkali,  nor  earth,  will  separate  the  acid 
from  the  barytes.     Potash,  which  has  a  very  strong  attraction  for 
the  acid,  will  not  decompose  it  alone  ;  but  if  potash  combined 
with  carbonic  acid  be  digested  for  some  time  with  powdered  sul- 
phate of  barytes,  there  is  a  double  decomposition  ;  and  combina- 
tions of  sulphuric  acid  and  potash,  and  carbonic  acid  and  barytes. 
are  formed."*  It  appears,  however,  from  experiment,  that  not  only 
may  the  decomposition  stated  take  place  to  a  certain  extent,  but 
that  likewise,  under  similar  circumstances,  sulphate  of  potash  will 
decompose  carbonate  of  barytes. 

148.  Mr.  Richard  Phillips  found,  that  on  boiling  100  parts  of 
sulphate  of  barytes  and  59  parts  of  carbonate  of  potash,  for  two 
hours,  in  four  ounces  of  water,  more  being  added,  from  time  to 
time,  to  supply  the  loss  from  evaporation,  23  parts  only  of  the  sul- 
phate of  barytes  were  decomposed,  producing  19.5  of  carbonate  of 
barytes.     As  the  converse  of  this  experiment,  he  then,  in  the  same 
manner,  boiled  85  parts  of  carbonate  of  barytes  with  74  of  sulphate 
of  potash,  and  found  that  57  parts  of  the  carbonate  were  decom- 
posed, yielding  67  parts  of  sulphate  of  barytes.     From  these  and 
other  experiments,  Mr.  Phillips  infers  that  the  complete  decompo- 
sition of  the  salts,  in  either  case,  is  prevented  by  the  reproduction, 
during  the  process,  of  the  insoluble  compounds. f     M.  Dulong 

Explain  separately  the  case  of  heating  and  of  solution? 
How  may  potash  be  made  to  decompose  sulphate  of  barytes? 
How  may  the  resulting  compounds  be  made   to  decompose  each  other 
and  to  reproduce  the  original  materials  ? 

State  the  experiment  of  Mr.  Phillips  on  these  materials? 
What  inference  was  drawn  from  that  experiment  ? 

*  Elements  of  Chemical  Philosophy,  p.  103. 

t  See  paper  "  On  an  Anomalous  Case  of  Chemical  Affinity,"  by  R.  Phil- 
lips, in  Jour,  of  Science,  ed.  at  R.  I.,  vol.  i. 


66  CHEMISTRY. 

had  been  previously  engaged  in  researches  on  the  same  subject, 
from  which  were  drawn  the  following  conclusions:  1.  That  all 
the  insoluble  salts  are  decomposed  by  the  carbonates  of  potash  or 
soda  ;  but  that  a  complete  exchange  of  principles  of  these  salts  can- 
not take  place.  2.  That  all  the  soluble  salts,  of  which  the  acid 
forms  with  the  base  of  the  insoluble  carbonate  an  insoluble  salt, 
are  decomposed  by  these  carbonates^  until  the  decomposition  has 
reached  a  certain  limit,  which  it  cannot  pass.* 

149.  (7.)  It  has  been  remarked,  in  the  discussion  of  the  pre- 
ceding law  of  chemical  affinity,  that  when  compound   bodies  are 
brought  within  the  sphere  of  each  other's  action,  they  may  be  mu- 
tually decomposed,  or  they  may  combine  to  form  sur-compounds. 
This  last  result  is  what  takes  place  when  acids  unite  with  metallic 
oxides  to  constitute  salts,  or  when  oils  and  alkalies  are  united  to 
form  soaps.      Hence  a  distinction  of  bodies  has  been  made  into 
primary  compounds  and  secondary  compounds  ,•  and  these  again  have 
been  variously  subdivided  by  systematic  writers.      The  primary 
compounds  are  not  all  formed  by  the  simple  union  of  two  bodies  : 
those  which  are  thus  constituted  may  be  termed  binary  compounds, 
which,  next  to  the  simple  bodies  themselves,  are  of  the  utmost 
importance.      Next   to   these  may  be  placed  the   primary  com- 
pounds with  double  bases;    such  are  the  tartaric,  citric,  malic, 
and  other  acids,  in  which  hydrogen  and  carbon  unite  to  form  the 
respective  bases,  which   combine  with  oxygen ;    the  prussic  or 
hydrocyanic  acid,  consisting  of  cyanogen,  a  compound  of  carbon 
and  nitrogen,  acidified  by  hydrogen ;  and  an  acid  which  has  been 
termed  the  hydrozanthic,  the  base  of  which  is  carbon  and  sulphur, 
as  in  the  last  case,  acidified  by  hydrogen. 

150.  The  primary  compounds  may  be  systematically  arranged 
in  three  principal  classes:   1.  Acids;  2.  Bases;  and  3.  Neutrals. 

The  term  Acid  was  formerly  used  to  denote  certain  substances 
characterized  by  their  sour  taste,  the  property  of  changing  the 
blue  colour  of  vegetables  to  red,  and  that  of  combining  with  alkalies 
and  certain  earths  to  form  salts,  or  as  they  were  termed  neutral 
salts  :  all  the  bodies  regarded  as  acids  being  liquids,  or  else  gases 
or  solids,  capable  of  being  readily  reduced  to  the  liquid  form,  by 
uniting  with  water.  Lavoisier  having  found  that  some  of  the 
most  powerful  of  the  acids,  as  the  sulphuric  and  the  nitric,  were 
composed  of  certain  bodies  united  to  a  large  proportion  of 
oxygen,  concluded  that  oxygen  was  the  general  acidifying  princi- 

What  were  Dulong's  conclusions  from  similar  experiments  ? 
What  two  different  effects  may  proceed  from  the  mixture  of  compound 
bodies? 

What  distinction  of  bodies  has  been  founded  on  this  difference  of  effects  ? 
To  what  class  of  bodies  is  the  term  binary  compound  applicable  ? 
Give  some  examples  of  primary  compounds  with  double  bases. 
What  are  the  three  classes  of  primary  compounds  ? 
How  was  the  term  acid  formerly  used  ? 

*  See  Annales  de  Chimie,  vol.  Ixxii. ;  and  Dr.  Ure's  Diet,  of  Chemistry 
art.  ATTRACTION. 


PRIMARY  CHEMICAL  COMPOUNDS.  67 

pie,  and  therefore  considered  all  acids  as  compounds  containing 
an  excess  of  oxygen. 

151.  This  doctrine  was  rendered  untenable  by  the  discovery  of 
properties  regarded  as  characteristic  of  acids,  (such  as  the  red- 
dening of   vegetable   blues,    and   the  formation   of   salts   with 
alkalies,)  in   the  compound  of  sulphur  with  hydrogen,  or  sul- 
phuretted hydrogen;  and  by  the  discovery  of  Davy  relative  to  the 
nature  of  chlorine,  and  the  constitution  of  muriatic  or  hydrochloric 
acid.    Subsequent  researches  have  furnished  reasons  for  extending 
the  appellation  of  acid  to  certain  compounds  of  chlorine,  iodine, 
bromine,  fluorine,  hydrogen,  sulphur,  selenium,  and  some  of  the 
metals  ;  and  the  acids  containing  oxygen  have  been  styled  oxacids, 
by  way  of  distinction.     On  the  same  principle  have  been  formed 
the  terms  chloracids,  iodacids,  bromacids,  fluoracids,  hydracids, 
sulphuracids,  &c.     But  the  state  of  science  at  present  hardly  en- 
ables us  to  discriminate  properly  between  such  of  the  various 
combinations  of  the  simple  substances  above  mentioned  as  cor- 
respond with  the  acid    compounds  of  oxygen,  and  those  corres- 
ponding with  the  oxides. 

152.  The   primary  compounds   called   Bases  include  such  as 
have  been  heretofore  termed  alkalies,  earths,  and  metallic  oxides. 
The  alkalies,  except  ammonia,  are  now  known  to  be  oxides ; 
three  of  the  four  alkalies  with  simple  bases,  lithia,  potash,  and 
soda,  being  oxides  of  certain  metals,  and  the  other  ammonia,  a 
combination  of  hydrogen  with  nitrogen,  which  might  therefore  be 
styled  nitroguret  of  hydrogen.    Besides  these,  there  are  a  number 
of  newly-discovered  alkalies,  having  compound  bases,  and  chiefly 
procurable  from  vegetable  substances,  as  morphine,  from  opium ; 
strychin,  from   nux   vomica;  and  cinchonin   and   quinine,   from 
Peruvian  bark.     Such  of  these  alkalies  as  have  been  analyzed  are 
found  to  be  oxides  with  bases  composed  of  various  proportions  of 
hydrogen  and  carbon,  and  in  some  cases  of  hydrogen,  carbon,  and 
nitrogen. 

153.  The  earths,  like  most  of  the  alkalies  with  simple  bases,  are 
metallic  oxides.    Silica,  however,  long  classed  among  the  earths, 
though  a  compound  of  oxygen  with  a  simple  base,  differs  from  the 
rest  in  various  respects,  acting  the  part  of  an  acid  in  the  formation 
of  the  numerous  mineral  compounds  in  which  it  is  contained. 

154.  Among  the  primary  compounds,  those  termed  chlorides, 
iodides,  bromides,  &c.,  with  most  of  which  we  are  yet  but  very 
imperfectly  acquainted,  will  nevertheless  probably  prove  to  be  an 
interesting  and  important  class  of  bodies ;  and  this  will  hardly  be 

What  was  Lavoisier's  view  of  the  constitution  of  all  acids? 
How  was  his  definition  of  an  acid  subverted  ? 
What  term  is  now  applicable  to  acids  formed  of  oxygen  ? 
What  terms  apply  to  the  other  classes  of  these  substances  ? 
What  is  meant  by  the  term  base  ? 

What  classes  of  bodies  formed  by  the  ancient  chemists  has  it  been  ap- 
plied to  signify  ? 

What  are  the  bases  of  the  newly  discovered  alkaline  bodiee? 


68  CHEMISTRY. 

questioned  when  it  is  considered  that  chloride  of  sodium,  or  com- 
mon salt,  and  chloride  of  calcium,  improperly  called  muriate  of 
lime,  are  among-  the  bodies  in  question. 

155.  Of  the  primary  compounds  termed  Neutrals,  it  will  be  suffi- 
cient here  to  state,  that  Dr.  Thomson  has  arranged  them  under 
seven  heads,  namely,  water,  alcohol,  volatile  oil,  fixed  oil,  bitu- 
men, and  ethal,  an  oleose  kind  of  matter  which  Chevreul,  a  French 
chemist,  procured  from  spermaceti. 

156.  The  most  important  of  the  secondary  or  sur-componnds, 
are  those  arising  from  the  combination  of  acids  with  bases.   Those 
best  known  are  the  compounds  of  the  oxacids  with  the  alkalies 
with  simple  bases,  or  with  certain  of  the  earths  and  metallic  ox- 
ides.   As  examples  maybe  mentioned,  sulphate  of  soda,  (glauber 
salt,)  nitrate  of  potash,  (salt-petre,)  sulphate  of  magnesia, (Epsom 
salt,)  and  acetate  of  lead  (sugar  of  lead.)     All  these,  as  well  as 
many  others  that  might  be  named,  are  readily  soluble  in  water;  thus 
corresponding  with  the  popular  notion  of  salts.     But  other  com- 
pounds of  acids  and  metallic  oxides  are  insoluble,  as  carbonate  of 
lime,  (chalk,)  sulphate  of  barytes,  (ponderous  spar,)  sulphate  of 
lead,  and  phosphate  of  mercury.     Some   salts   have   compound 
bases,  as  alum,  which  is   a   sulphate  of  potash  and  alumine ; 
nitrate  of  ammonia  and  magnesia,  phosphate  of  ammonia  and  soda, 
sulphate  of  ammonia,  and  oxide  of  iron,  muriate  of  ammonia  and 
magnesia,  &c.    The  acids  with  compound  bases  also  unite  with  the 
alkaline  and  other  bases  to  form  salts.   Of  this  description  are  the 
sulpho-cyanate  of  lime,  the  salts  formed  by  the  prussic  acid,  and 
the  numerous  salts  formed  by  the  acetic,  tartaric,  and  other  hydro- 
carbonous  acids. 

157.  It  was  from  the  analysis  of  the  neutral  salts,  and  the  ob- 
servation of  the  relation  of  the  combining  quantities  of  the  various 
salts  to  each  other,  that  Wenzel  and  Richter  were  led  to  those 
speculations  on  chemical  affinities,  which  furnished  a  foundation 
for  the  more  extensive  researches  of  Dalton,  Berzelius,  and  other 
philosophers,  relative  to  the  theory  of  definite  proportions.     As 
binary  compounds  consist  of  certain  numbers  of  atoms  or  equiva- 
lents of  their  constituent  parts,  so  when  they  enter  into  new  com- 
binations,  forming   sur-compounds,   they   unite    in    proportions 
which  bear  certain  relations  to  the  combining  numbers  of  those 
censtituents.     Thus  the  combining  numbers  or  equivalents    of 
compound  bodies,  as  salts,  are  the  sums  of  those  of  the  acids  and 
bases  of  which  they  are  formed.   As,  for  instance,  potash  consists 
of  potassium,  atomic  weight  40,  and  oxygen,  atomic  weight  8,  and 
as  it  contains  an  atom  of  each,  its  combining  number,  or  atomic 

What  is  the  true  chemical  nature  of  the  earths  ? 
How  many  bodies  are  included  under  the  term  neutrals'*. 
What  are  the  most  interesting  among  our  compound  bodies  ? 
Give  some  examples  of  these  bodies. 
Name  the  salts  and  acids  which  have  compound  bases. 
What  investigation  furnished  the  foundation  of  the  prevailing  theories 
respecting  chemical  proportions  ? 


SIMPLE  BODIES  AND  THEIR  PRIMARY  COMPOUNDS.  69 

weight  is  48;  so  sulphuric  acid  is  composed  of  sulphur,  atomic 
weight  16,  and  oxygen  8,  and  consisting  of  one  atom  of  sulphur 
to  three  of  oxygen,  its  atomic  weight  must  be  3x8=244-16=40; 
hence  sulphate  of  potash  will  have  for  its  combining  weight  48+ 
40=88. 

158.  The  atomic  weights  or  combining  proportions  of  other 
salts  are  in  the  same  manner  derived  from  those  of  their  constitu- 
ents ;  and  when  they  enter  into  new  chemical  combinations,  such 
always  take  place  with  reference  to  their  atomic  weights,  or  mul- 
tiples of  those  weights. 

Berzelius  concludes,  from  numerous  experiments  on  a  vast 
variety  of  bodies,  that  the  law  of  combination  by  definite  propor- 
tions, pervades  the  whole  of  nature,  and  that  it  extends  not  only 
throughout  the  productions  of  the  mineral  kingdom,  but  also  to 
those  derived  from  animals  and  vegetables. 

Simple  Bodies  and  their  Primary  Compounds. 

159.  Among  those  that  are  considered  as  elementary  bodies, 
many  seem  to  be  of  little^^hportance  in  the  economy  of  nature, 
since  they  are  never  found  in  an  uncombined  state ;  and  from  the 
most  recent  researches  of  chemists,  it  may  be  concluded  that  they 
exist  but  in  minute  quantities  in  their  several  compounds.     It  is 
from  the  union  of  a  few  elementary  or  simple  substances,  that  the 
vast  variety  of  the  forms  of  matter  observable  in  the  animal,  vege- 
table, and  mineral  kingdoms,  are  chiefly  produced.    Of  organized 
bodies,  though  their  proximate  elements  are  often  the  result  of 
complicated  combinations,  yet  the  ultimate  products  from  analysis, 
are  generally  few  in  number. 

160.  Vegetables,  when  their  complete  decomposition  is  effected, 
are  found  to  consist  principally  of  oxygen,  hydrogen,  and  carbon; 
and  animal  matter,  when  submitted  to  the  crucible  of  the  chemist, 
hardly  yields  a  greater  variety  of  products,  being  chiefly  distin- 
guishable from  vegetable   substances,  as  affording   nitrogen    or 
azote,  in  addition  to  the  simple  bodies  just  mentioned.     It  is  true 
that  sulphur,  phosphorus,  and  some  of  the  metals,  as  iron  and  man- 
ganese, sometimes  enter  into  the  composition  of  both  animals  and 
vegetables,   but  in  relatively  small  quantities.     In  the   mineral 
kingdom,  a  more  copious  variety  of  ultimate  products  occurs,  in- 
cluding, of  course,  those  simple  bodies  which  are  not  found  in 
animals  or  vegetables.     But  even  here  the  ultimate  elements  of 
the  great  masses  which  constitute  the  mineral  crust  of  the  terres- 
trial globe  are  so  distributed,  that  a  relatively  small  number  of 

How  are  the  combining  numbers  of  compound  bodies  related  to  those 
of  their  constituents  ? 

How  is  this  illustrated  in  the  case  of  sulphate  of  potash  ? 

How  extensive,  according  to  the  researches  of  Berzelius,  is  the  law  of 
chemical  combination  ? 

Of  what  simple  bodies  are  vegetables  composed  ? 

Of  what  ones  are  animal  substances  constituted  ? 

In  which  of  the  three  great  departments  of  nature  is  the  largest  number 
of  simple  bodies  found  ? 


70  CHEMISTRY. 

them  only  enter  into  the  composition  of  the  most  abundant  and 
widely  distributed  compounds. 

161.  Some  interesting  speculations  on  the  relative  qualities  of 
the  simple  substances  contained  in  the  earth's  crust,  have  been 
advanced  by  Mr.  De  La  Beche. 

"The  principal  substances  entering  into  the  chemical  compo- 
sition of  our  planet's  surface  may  be  classed  in  the  following 
order,  according  to  the  respective  importance  of  each  : 

Simple  Non-metallic  Substances. 

1.  Oxygen      I  3.  Nitrogen  I  5.  Sulphur    I  7.  Fluorine 

2.  Hydrogen  j  4.  Carbon      |  6.  Chlorine  |  8.  Phosphorus. 

Metallic  Bases  of  the  Alkalies  and  Earths. 

1.  Silicium*       I      3.  Potassium      I      5.   Magnesium 

2.  Aluminum  4.  Sodium  6.   Calcium. 

Metals,  the  Oxides  of  which  are  neither  Earths  nor  Alkalies. 
1.  Iron  |  Manganese. 


"  It  would  appear,  therefore,  that  smeen  substances,  commonly 
considered  simple,  constitute,  by  their  various  combinations,  if  not 
entirely,  at  least  by  far  the  largest  amount  of  all  the  matter  which, 
cither  gaseous,  liquid,  or  solid,  organic  or  inorganic,  is  known  to 
exist  on  the  surface  of  the  earth.  "f 

162.  Since,  then,  these  bodies,  through  their  relative  affinities, 
exercise  so  extensive  an  influence  over  that  portion  of  the  universe 
with  which  we  are  acquainted,  they  obviously  claim  the  fullest 
investigation,  with  respect  to  their  individual  properties  and  seve- 
ral combinations.  Some  of  those  bodies,  however,  which  are 
comparatively  rare,  are  still,  on  various  accounts,  curious  and 
interesting;  and  all  the  simple  substances  require  some  further 
notice.  The  following  pages,  therefore,  will  contain  a  brief 
account  of  the  chemical  properties  of  the  simple  bodies  of  both 
classes,  and  of  those  of  their  most  important  compounds. 

163.   Table  of  t  he  Binary  Compounds  of  the  Non-metallic  Elements. 
Chlorine. 

Protoxide,  1  Ch.  1  Ox. 
Peroxide,  1  Ch.  4  Ox. 
Chloric  acid,  1  Ch.  5  Ox. 
Oxychloric  acid,  1  Ch.  7  Ox. 
Muriatic  acid,  1  Ch.  1  Hyd. 

How  has  De  la  Beche  arranged  the  substances  composing  the  crust  of 
the  earth? 

Enumerate  the  first  class  of  these  substances,  —  the  second,  —  the  third. 
Give  the  names  and  combining  ingredients  of  the  compounds  of  chlorine. 

*  Mr.  De  la  Beche  ranks  the  base  of  siliceous  earth  among  the  metals; 
bat  Berzelius  and  other  recent  writers  reckon  it  among  the  non-metallic 
elements.  See  p.  22,  No.  38. 

t  Researches  on  Theoretical  Geology,  1834,  pp.  23  24. 


COMPOUNDS  OF  THE  NON-METALLIC  ELEMENTS.  71 

Iodine. 

lodic  acid,  1  I.  5  Ox. 
Chloriodic  acid,  2  I.  1  Ch. 

Bromine. 

Bromic  acid,  1  Br.  5  Ox. 
Chloride  of  bromine. 

Fluorine. — Hydrofluoric  acid,  1  Fl.  1  Hyd. 

Hydrogen. 

Water,  1  H.  1  O. 
Peroxide  of  hydrogen,  1  H.  2  Ox. 
Muriatic  acid,  1  H.  1  Ch. 
Hydriodic  acid,  1  H.  1  I. 
Hydrobromic  acid,  1  H.  1  B. 
Hydrofluoric  acid,  1  H.  1  F, 

Nitrogen. 

Atmospheric  air. 

Nitrous  oxide,  1  N.  1  Ox. 

Nitric  oxide,  1  N.  2  Ox. 

Hyponitrous  acid,  1  N.  3  Ox. 

Nitrous  acid,  1  N.  4.  Ox. 

Nitric  acid,  1  N.  5  Ox. 

Chloride  of  nitrogen,  1  N.  3  Ch. 

Iodide  of  nitrogen,  1  N.  3  I. 

Ammonia,  or  nitroguret  of  hydrogen,  1  N.  3  H. 

Carbon. 

Carbonic  oxide,  1  C.  1  Ox. 
Carbonic  acid,  1  C.  2  Ox. 
Oxalic  acid,  2  C.  3  Ox. 
Protochloride  of  carbon,  1  C.  1  Ch. 
Perchloride  of  carbon,  2  C.  3  Ch. 
Iodide  of  carbon,  1  C.  1  I. 
Sesqui-iodide  of  carbon,  2  C.  3  I. 
Bromide  of  carbon. 
Subcarburet  of  hydrogen,  1  C.  2  H. 
Carburet  of  hydrogen,  2  C.  2  H. 

How  many  compounds  of  iodine  are  enumerated  by  chemists  ? 

How  many  of  bromine? 

What  is  the  constitution  of  water  ? 

What  is  that  of  peroxide  of  hydrogen 

How  many  compounds  are  there  of  nitrogen  and  oxygen? 

What  is  the  composition  of  atmospheric  air  ? — of  nitrous  oxide  ? — nitric 
acid? 

How  many  and  what  compounds  does  carbon  form  with  oxygen  ? — how 
many  with  chlorine  ? — with  iodine  ? 

How  many  and  what  compounds  are  formed  of  hydrogen  and  carbon  ? 


72  CHEMISTRY. 


Carbon  continued. 

Bicarburet  of  hydrogen,  2  C.  1  H. 

Quadricarburet  of  hydrogen,  4  C.  4  H. 

Naptha. 

Caoutchouc. 

Cyanogen,  2  C.  IN. 

Boron. 

Boracic  acid,  1  B.  2  Ox. 
Chloride  of  boron,  1  B.  2  Ch. 
Fluoride  of  boron,  1  B.  3  F. 

Silicon. 

Silex  or  silicic  acid,  1  Si.  3  Ox. 
Chloride  of  silicon. 
Fluoride  of  silicon,  1  Si.  1  F. 

Phosphorus. 

Phosphorus  acid,  2  Ph.  3  Ox. 
Phosphoric  acid,  2  Ph.  5  Ox. 
Hypophosphorous  acid,  2  Ph.  1  Ox. 
Chloride  of  phosphorus,  1  Ph.  1  Ch. 
Perchloride  of  phosphorus,  1  Ph.  2  Ch. 
Iodide  of  phosphorus. 
Periodide  of  phosphorus,  1  Ph.  2  I. 

Bromides  of  phosphorus,  * 


Phosphuretted  hydrogen,  1  Ph.  1  H. 
Subphosphuretted  hydrogen,  1  Ph.  3  H. 
Phosphuret  of  carbon,  1  Ph.  1  C. 

Sulphur. 

Hyposulphurous  acid,  1  S.  1  Ox. 
Sulphurous  acid,  1  S.  2  Ox. 
Hyposulphuric  acid,  2  S.  5  Ox. 
*^  Sulphuric  acid,  1  S.  3  Ox. 

Chloride  of  sulphur,  1  S.  1  Ch. 
Iodide  of  sulphur. 
Bromide  of  sulphur. 
Sulphuretted  hydrogen,  1  S.  1  H. 
Supersulphuretted  hydrogen. 

Enumerate  the  compounds  of  boron  and  those  of  silicon  with  the  pro- 
portions of  each  ? 

With  how  many  simple  non-metallic  substances  does  phosphurus  unite  ? 

How  many  of  its  compounds  are  acids  ? 

What  two  compounds  and  in  what  proportions  does  it  form  with  hydro- 
gen? 

How  many  of  the  non-metallic  bodies  are  capable  of  combining  with 
sulphur  ? 

How  many  of  the  compounds  of  sulphur  have  acid  properties  ? 


OXYGEN. 

Sulphur  continued. 

Sulphuret  of  carbon,  2  S.  1  C. 
Sulphuret  of  phosphorus,  1  S.  1  Ph. 

Selenium. 

Selenious  acid,  1  Se.  2  Ox. 
Selenic  acid,  1  Se.  3  Ox. 
Protochloride  of  selenium,  2  Se.  1  Ch. 
Perchloride  of  Selenium,  1  Se.  1  Ch. 
Hydroselenic  acid,  1  Se.  1  H. 


73 


Oxygen. 

164.  The  gaseous  body  named  by  the  French  chemists  oxygen, 
or  the  acidifying  principle,*  may  be  obtained  in  a  simple  or  un- 
combined  state  by  several  different  processes,  and  especially  by 
the  application  of  heat  to  the  combination  of  oxygen  with  certain 
metals,  as  mercury,  manganese,  or  lead. 


The  apparatus  exhibibited  above  affords  a  convenient  method 
for  the  production  of  this  gas  by  the  decomposition  of  metallic 
oxides.  Let  a  small  quantity  of  red  oxide  of  lead,  (minium  or 
red  lead,)  be  introduced  into  the  retort  A,  the  beak  or  opening  of 
which  is  connected  with  the  double-necked  glass  globe  B,  from 
which  proceeds  the  bent  tube  C,  terminating  under  the  tall  glass 
jar  E,  the  lower  end  of  which  is  immersed  in  the  water-trough  G. 
If  then  the  retort  be  heated  by  a  lamp,  after  the  atmospheric  air, 
contained  in  the  vessel  and  tube  has  been  suffered  to  escape,  the 
cylindrical  jar  filled  with  water  and  inverted,  is  to  be  placed  over 
the  lower  end  of  the  tube,  as  represented  in  the  figure ;  and  the 
oxygen  gas,  as  it  is  formed  by  the  decomposition  of  the  oxide, 
will  pass  over,  and  rising  in  bubbles  through  the  water  in  the 
jar,  will  collect  in  the  upper  part  of  it. 

165.  This  gas  may  be  procured  in  the  same  manner,  by  sub- 
How  many  compounds  does  selenium  form  with  other  non-metallic 
bodies  ? 

Delineate   and  explain  the  apparatus  for  procuring  oxygen  from  red 
lead. 


*  From  the  Gr.  O£v$,  acid,  and  Tevvao),  to  generate,  or  produce.  The  Ger- 
man chemists  style  this  body  SAUERSTOFF,  literally  sour  stuff. 

G 


74  CHEMISTRY. 

tituting  for  the  oxide  of  lead,  red  oxide  of  mercury,  or  black 
oxide  of  manganese.  This  last  being  a  cheap  substance,  is  general- 
ly used  for  obtaining  oxygen  gas  on  a  large  scale ;  and  for  that 
purpose  the  distillation  is  conducted  in  an  iron  retort,  luted  to  a 
gun-barrel,  and  the  former  exposed  to  the  heat  of  a  furnace.  When 
obtained  by  this  last  mode,  however,  the  gas  is  not  very  pure,  and 
the  quantity  produced  from  a  given  weight  of  the  oxide  is  extremely 
variable. 

166.  For  purposes  of  illustration,  the  method  of  procuring  oxy- 
gen most  readily  and  abundantly  is  that  of  placing  in  an  iron 
mercury  bottle,  which  may  be  had  for  50  cents  or  $1,  a  quan- 
tity, say  lib.,  of  salt-petre ;  into  the  mouth  of  the  bottle  one  end 
of  a  gun  barrel  is  screwed,  while  to  the  other,  which  is  bent 
downward,  is  adapted  a  flexible  leaden,  or  other  tube,  to  conduct 
the  gas  into  the  pneumatic  cistern,  gas  holder,  or  bag  by  which  it 
is  to  be  received. 

167.  As  there  is  a  great  number  of  substances  in  which  oxygen  is 
contained,  so  it  may  be  procured  by  various  other  processes.  When 
wanted  for  experiments  of  research,  and  therefore  in  a  state  of  the 
greatest  purity,  about  100  grains  of  salt  called  chloride  of  potassa, 
(formerly  oxymuriate  of  potash,)  may  be  introduced  into  a  retort 
with  a  bent  tube  fitted  to  it,  the  open  end  of  which  must  pass  under 
the  mouth  of  a  jar  filled  and  inverted  in  a  water  trough.     The  re- 
tort is  then  to  be  heated  by  the  flame  of  a  large  spirit-lamp,  and 
after  the  atmospheric  air  contained  in  it  has  been  driven  off,  and 
the  salt  fuses  and  appears  to  boil,  oxygen  gas  will  be  formed,  and 
may  be   collected  as  before,  in  the  jar  over  the  water-trough. 
About  100  cubic  inches  of  gas  may  be  thus  obtained,  from  the 
specified  quantity  of  the  chlorate. 

168.  Oxygen   gas  may  also  he  obtained  slowly  and  in  small 
quantities,  through  the  decomposition  of  water,  by  living  vegeta- 
bles exposed  to  the  action  of  the  sun's  light.     This  may  be  de- 
monstrated by  filling  an  eight-ounce  phial  with  water,  and  after 
having  introduced  into  it  a  sprig  of  mint,  inverting  it  in  a  basin  of 
water.     If  this  be  placed  in  a  window,  or  any  other  situation  ex- 
posed to  the  light,  minute  bubbles  will  soon  be  perceived  forming 
on  the  surface  of  the  leaves,  and  gradually  accumulating,  they 
will   rise   to  the    upper  part   of  the   bottle,  where  after  a  few 
days  a  variable  quantity  of  the  gas  will  be  collected,  exhibiting, 
if  the  experiment  be  carefully  made,  a  considerable  degree  of 
purity. 

169.  Oxygen  gas,  when  pure,  by  whatever  method  obtained,  is 
perfectly  transparent,  and  destitute  of  taste  or  smell,  exceeding- 
atmospheric  air  in  a  slight  degree  in  specific  gravity.   It  is  neces- 
sary for  the  support  of  animal  life  by  respiration,  and  it  may  be 
breathed  alone  for  some  time  with  safety.     Indeed,  an  animal 

In  what  manner  is  this  gas  procured  in  the  greatest  purity  ? 
How  may  it  be  procured  from  vegetable  substances  ? 
What  are  the  chief  sensible  properties  of  oxygen  gas? 


OXYGEN.  75 

confined  in  a  small  vessel,  filled  with  this  gas,  will  live  nearly 
three  times  as  long  as  if  confined  in  an  equal  bulk  of  common  air, 
and  hence  oxygen  has  been  called  vital  air :  yet  it  appears,  that  if  an 
animal  be  kept  in  an  atmosphere  of  oxygen  gas,  and  obliged  to 
breathe  it  for  a  long  time,  great  excitement  will  be  produced,  in- 
flammatory action  will  take  place,  and  death  frequently  follow. 
Hence  this  gas,  though  a  powerful  supporter  of  life  in  the  diluted 
state  in  which  it  is  found  in  atmospheric  air,  cannot  be  used  alone 
with  safety,  except  for  a  very  short  period.  It  is  absorbed  by  water 
only  in  a  minute  proportion,  and  therefore  is  usually  collected  iu 
jars  over  that  fluid.  It  does  not,  like  acids  or  alkalies,  alter  the 
colour  of  paper  tinged  with  tincture  of  litmus  or  syrup  of  violets, 
nor  does  it  render  lime-water  turbid. 

170.  The  most  important  effects  of  oxygen  are  those  which  arise 
from  its  powerful  influence  as  a  supporter  of  combustion.     All 
inflammable  bodies  burn  in  this  gas,  with  a  greater  display  of 
heat  and  light  than  in  atmospheric  air.     Several  interesting  ex- 
periments to  illustrate  this  principle  may  be  made  by  including 
oxygen  gas  in  a  strong  glass  bottle,  closely  stopped  with  a  cork, 
having  a  piece  of  wire  passed  through  it.    If  the  cork  be  removed, 
and  a  wax  taper  lighted  and  just  blown  out  be  quickly  introduced 
into  the  bottle,  it  will  be  immediately  rekindled,  and  burn  with  a 
large  vivid  flame. 

171.  A  sulphur  match,  just  lighted,  and  held  in  the  bottle  of 
gas,  will  also  burn  brilliantly,  with  a  beautiful  purple  colour. 
A  piece  of  charcoal  fixed  to  the  wire,  and  made  red-hot,  if  immersed 
in  the  gas,  will  burn  with  great  splendour,  throwing  off  beau- 
tiful sparks.     A  bit  of  phosphorus  about  the  size  of  a  pea  may  be 
stuck  on  the  wire,  and  if  then  kindled  and  immediately  plunged 
in  the  gas,  it  will  burn  with  the  most  intense  light,  the  splendour 
of  which  is  painful  to  the  eye.     But  one  of  the  most  striking  in- 
stances of  combustion  in  oxygen  is  that  of  iron  wire.     For  the 
purpose  of  this  experiment,  a  large  jar  should  be  used,  filled  with 
very  pure  oxygen  gas,  and  placed  over  water  in  a  shallow  dish. 
A  small  coil  is  to  be  formed  by  twining  a  thin  piece  of  iron  wire, 
such  as  an  annealed  watch-spring,  or  small  harpsicord  wire,  round 
the  stem  of  a  tobacco-pipe,  and  then  fixing  it  to  a  cork  float ;  the 
extremity  of  the  wire  being  dipped  in  melted  sulphur,  and  ignited, 
is  to  be  introduced  under  the  jar,  when  the  iron  will  burn  with  a 
brilliant  light,  throwing  off  scintillations  like  fire  works. 


What  connexion  has  it  with  animal  existence  ? 

What  name  did  it  formerly  receive  from  this  circumstance  ? 

What  results  from  long  continued  confinement  of  an  animal  in  this 
air  ? 

What  dispostion  has  it  to  mix  with  water  ? 

Oxygen  is  an  acidifying  principle, — has  it  any  acid  properties  of  its 
own  ? 

What  is  its  most  important  effect  ? 

Stale  some  of  the  phenomena  of  combustion  exhibited  in  oxygen. 

How  may  the  combustion  of  iron  in  this  gas  be  effected  ? 


76 


CHEMISTRY. 


172.  As  an  illustration  of  the  vivid 
action  of  oxygen  on  combustibles, 
we  may  refer  to  tbe  annexed  repre- 
sentation of  the  combustion  of  a  piece 
of  steel  watch  spring,  within  a  glass 
vessel  containing  a  quantity  of  the 
gas.  Having  filled  the  bottle  from 
any  convenient  reservoir,  the  cork, 
to  which  is  connected  a  thick  brass 
wire,  with  a  knob  at  one  end,  and 
pair  of  nippers  to  hold  the  spring 
at  the  other,  we  insert  the  spring 
and  cork  into  their  place,  while  the 
mouth  is  yet  inverted  in  water,  or 
holding  the  hand  over  the  mouth 
while  it  is  inverted,  we  may,  with- 
out serious  inconvenience,  insert 
them  while  the  bottle  is  erect.  A 
knob  rises  from  the  metallic  base,  cemented  to  the  bottom  through 
a  hole  in  its  centre.  By  this  arrangement  the  ignition  may  be  com- 
menced by  electricity  from  the  battery. 

173.  In  all  the  experiments  above  described,  and  other  cases  of 
the  combustion  of  inflammable  bodies  in  oxygen  gas,  combinations 
take  place  between  the  oxygen  and  the  combustible,  and  new  pro- 
ducts arise  possessing  peculiar  properties.     The  heat  and  light 
given  out  in  these  cases,  if  considered  as  depending  on  the  pre- 
sence of  certain  ethereal  imponderable  fluids,  may  be  supposed  to 
have  been  previously  combined  with  the  oxygen,  and  thus  the 
gas  may  be  conceived  to  consist  of  a  ponderable  basis,  combined 
with  heat  or  caloric  and  light,  the  evolution  of  which  takes  place 
on  the   union  of  the  basis  with  the  combustible  body.     Hence 
when  experiments  of  this  nature  are  executed  with  due  care  and 
accuracy,  the  product  of  combustion  ought  to  be  exactly  equal  in 
weight  to  the  joint  quantities  of  oxygen  gas  and  combustible 
matter  which  enter  into  its  composition;  and   this  is  found  to  be 
the  case.     Thus  when  phosphorus  is  burned  in  oxygen  gas,  a 
white  flaky  substance  will  be  obtained,  which  is  phosphoric  acid ; 
and  its  weight  will  be  that  of  the  phosphorus  consumed,  added  to 
that  of  the  gas  which  it  has  absorbed.     So  in  burning  iron  wire, 
a  combination  will  be  produced  of  the  iron  with  oxygen,  forming 
a  metallic  oxide,  the  weight  of  which  will  be  equal  to  that  of  its 
component  parts  added  together. 

174.  The  products  of  the  combustion  of  bodies  in  oxygen  gas  may 


Explain  the  apparatus  for  igniting  a  steel  spring  in  oxygen  by  means 
of  electricity. 

What  are  the  results  of  the  combustion  of  various  substances  in  oxygen  ? 

What  relation  by  weight,  ought  to  subsist  between  the  body  consumed 
the  oxygen  which  disappears,  and  the  product  obtained  ? 

How  is  this  exemplified  and  proved  ? 


OXIDES  AND  ACIDS.  77 

be  either  gaseous,  liquid,  or  solid,  according  to  circumstances  :  but, 
considered  as  chemical  compounds,  all  the  combinations  of  oxygen 
with  other  bodies  may  be  arranged  in  two  classes,  namely  oxides 
and  acids.  Both  these  classes  of  compounds  include  varieties, 
depending  on  the  different  proportions  of  oxygen,  united  respec- 
tively with  the  several  metallic  and  other  substances  which  enter 
into  their  composition.  Thus  with  iron,  oxygen  forms  two  differ- 
ent oxides,  called  from  their  colours  red  oxide  and  black  oxide ; 
but  the  former,  as  containing  the  smallest  quantity  of  oxygen,  is 
more  properly  called  the  protoxide  of  iron;  and  the  latter,  in 
which  it  contains  the  largest  quantity,  is  called  the  peroxide. 

175.  With  some  bodies  oxygen  forms  three  or  more  oxides; 
to  distinguish  which  have  been  introduced  the  terms  deutoxide, 
or  second  oxide;  tritoxide,  or  third  oxide,  &c.  Some  bodies  form 
oxides  alone  with  oxygen,  others  acids  only;  but  there  are  many 
which  form  both  oxides  and  acids.  The  relative  quantity  of 
oxygen  in  this  last  kind  of  combination  is,  as  already  stated, 
greater  in  the  acids  than  in  the  oxides.  When  a  body  forms  two 
acids  with  oxygen,  that  which  contains  the  smaller  quantity  is 
designated  by  a  term  ending  in  the  syllable  ous,  and  that  contain- 
ing a  larger  quantity  receives  a  name  ending  in  ic :  thus  we  have 
sulphurous  and  sulphuric  acids.  When  oxygen  combines  with 
any  substance  in  more  than  two  proportions  to  form  acids,  the 
term  hypo  is  prefixed,  to  distinguish  an  acid  with  an  inferior 
quantity  of  oxygen:  thus  hyposulphurous  acid  contains  a  smaller 
proportion  of  oxygen  than  sulphurous  acid,  and  hyposulphuric  acid 
less  than  sulphuric. 

176.  The  salts  formed  by  the  combination  of  acids  and  oxides 
are  also  distinguished  by  the  terminations  of  their  names :  thus 
those  produced  by  acids  with  names  ending  in  ous  are  distinguish- 
ed by  the  termination  ite,  as  sulphite  of  potash  ;  and  salts  formed 
by  acids  with  the  termination  ic,  have  names  terminating  in  ate, 
as  sulphate  of  potash.  This  method  of  nomenclature  has  been 
extended  to  other  compounds  besides  those  of  oxygen :  thus  the 
combinations  of  chlorine  which  are  not  acid,  are  called  chlorides; 
those  of  iodine,  iodides;  and  those  of  fluorine,  fluorides;  and  their 
acids,  and  the  salts  which  they  form,  are  designated  in  an  analogous 
manner,  as  hydrochloric  acid,  hydriodic  acid,  hydrofluoric  acid, 
hydrochlorate  of  ammonia,  &c.  The  compounds  formed  by  simple 

What  differences  in  the  mechanical  and  chemical  properties  of  products 
of  combustion  are  found  to  exist? 

What  are  the  two  classes  of  chemical  products  ? 

What  terms  are  employed  to  designate  the  various  degrees  of  oxygena- 
tion  in  the  same  substance  ? 

What  terms  are  commonly  employed  when  only  two  degrees  are  possible  ? 

What  terms  apply  to  the  several  acids  which  oxygen  may  form  with  the 
same  substance  ? 

In  what  terminations  do  words  end  which  designate  the  salts  formed 
by  the  several  acids  ? 

To  what  other  classes  of  bodies  has  the  nomenclature  formed  for  oxy- 
gon been  applied  I 


78 


CHEMISTRY. 


combustible  bodies,  as  those  of  sulphur,  carbon,  and  phosphorus, 
with  each  other,  or  with  metals,  are  distinguished  by  the  termi- 
nation uret,  as  phosphuret  of  carbon,  sulphuret  of  iron,  &c.  The 
terms  of  ii-phosphuret,  Zu'-carburet,  &c.,  are  used  to  denote  com- 
pounds containing  twice  as  much  phosphorus,  carbon,  &c.,  as 
a  phosphuret  or  a  carburet. 

Chlorine. 

111.  This  is  a  permanently  elastic  or  gaseous  fluid,  at  the  com- 
mon temperatures  and  pressures  of  the  atmosphere.  But  Mr. 
Faraday  ascertained  that  this  gas,  when  subjected  in  the  nascent 
state  to  a  degree  of  pressure  equal  to  about  four  atmospheres,  at 
the  temperature  of  60°,  becomes  condensed  into  a  liquid.*  Chlo- 
rine gas  has  a  greenish-yellow  colour,  and  a  pungent,  disagreeable 
odour ;  and  it  proves  highly  deleterious  when  respired. 

178.  It  may  be  obtained  from  the  decomposition  of  its  com- 
pounds, the  most  common  of  which  is  marine  or  culinary  salt, 
formerly  termed  by  chemists  muriate  of  soda,  but  which  is  now 
known  to  consist  of  chlorine  united  with  sodium  or  the  metallic 
basis  of  soda,  and  is  therefore  called  chloride  of  sodium.  Its 
decomposition  may  be  conveniently  effected  by  means  of  the 
apparatus  represented  in  the  annexed  diagram. 

Mix  one  part  of  black 
oxide  of  manganese  with 
three  parts  of  common  salt, 
both  finely  powdered,  and 
having  introduced  the  mix- 
ture into  the  tubulated  retort 
A,  pour  over  it  two  parts  by 
weight  of  sulphuric  acid,  di- 
'luted  with  an  equal  weight 
of  water ;  then  pass  the  beak  of  the  retort  under  the  inverted  glass 
jar  C,  filled  with  warm  water.  Now  on  lighting  the  lamp  beneath 
the  retort,  its  contents  will  become  gradually  heated,  and  the  sul- 
phuric acid  acting  upon  the  manganese,  which  is  in  the  state  of  a 
peroxide,  will  expel  a  part  of  its  oxygen  and  reduce  it  to  a  pro- 
toxide ;  the  liberated  oxygen  will  then  decompose  the  chloride 
of  sodium,  combining  with  its  metallic  basis,  while  the  chlorine, 
set  free,  in  the  gaseous  state,  will  be  driven  off  and  carried  into 
the  inverted  jar,  rising  in  bubbles  through  the  water.  The  sul- 

What  termination  is  given  to  terms  expressing  the  binary  compounds  of 
combustibles  ? 

What  is  the  state  of  chlorine  at  ordinary  temperatures  ? 

What  discovery  has  been  made  by  Mr.  Faraday  ' 

What  are  its  distinguishing  sensible  properties  ? 

By  what  means  is  it  most  easily  obtained  ? 

Over  what  liquid  may  it  be  collected  ? 

What  is  the  true  nature  of  the  process  when  chlorine  is  obtained  from 
common  salt  and  oxide  of  manganese  ? 

*  See  abstracts  of  Papers  in  Philos.  Trans.,  vol.  ii.  p.  190. 


Mr.  Faraday  in  regard  to  its  state  ? 
e  properties  ^ 


CHLORINE.  79 

phuric  acid  will  unite  with  the  oxide  of  sodium  (soda)  as  fast  as 
it  is  formed,  and  thus  the  decomposition  of  the  chloride  is  more 
readily  effected.  Chlorine  gas  may  in  like  manner  be  procured 
from  the  decomposition  of  muriatic  or  hydrochloric  acid,  by  means 
of  the  peroxide  of  manganese. 

179.  Water  at  the  temperature  of  about  60°  absorbs  twice  its 
volume  of  this  gas.     It  should  therefore  be  collected  over  warm 
water  which  absorbs  it  but  sparingly ;  or  it  may  be  received  in  a 
bottle  filled  with  atmospheric  air,  by  making  use  of  a  tube  which 
passes  nearly  to  the  bottom  of  the  bottle,  and  the  chlorine  gas,  as 
it  is  driven  over,  being  heavier  than  common  air,  will  gradually 
expel  it  and  fill  the  bottle,  exhibiting  its  peculiar  green  colour. 
The  specific  gravity  of  this  gas,  compared  with  common  air,  is 
2.47,  or  about  2£  times  the  weight  of  atmospheric  air.* 

180.  Chlorine  undergoes  no  alteration  when  exposed  to  a  high 
temperature  ;  and  even  theintense  heat  produced  by  a  Voltaic  bat- 
tery does  not  effect  any  change  of  the  properties  of  this  gas. 
When  a  burning  taper  is  plunged  into  a  bottle  of  chlorine  gas,  its 
flame  assumes  a  dull  red  colour,  a  dense  black  smoke,  containing 
much  carbon,  is  given  off,  and  after  the  combustion  has  thus  con- 
tinued a  short  time,  the  taper  becomes  extinguished.     Phospho- 
rus, and  several  of  the  metals  in  a  divided  state,  as  tin,  copper, 
and  zinc,  are  spontaneously  ignited  by  this  gas,  and  burn  in  it 
brilliantly. 

181.  Chlorine  and  oxygen  have  but  a  weak  affinity  for  each 
other ;  but  they  may  be  made  to  combine  by  indirect  means,  so  as 
to  form  at  least  four  distinct  compounds.   The  protoxide  of  chlorine, 
containing  36  parts  of  chlorine  and  8  of  oxygen,  or  one  combining 
atom  of  each,  was  discovered  by  Sir  H.  Davy,  who  gave  it  the 
name  of  euchlorine,  from  its  peculiar  deep  yello wish-green  hue. 
It  may  be  obtained  by  heating  slowly  in  a  glass  retort  2  parts  of 
the  salt  called  chlorate  of  potash,  (formerly  oxymuriate  of  pot- 
ash,) with  one  part  of  muriatic  acid,  when  the  protoxide  will  pass 
over  in  the  state  of  gas,  and  may  be  collected  over  mercury,  in  an 
inverted  jar.     The  retort  should  be  heated  by  means  of  a  water- 
bath,  as  the  gas  is  very  readily  exploded.     It  differs  much  in  its 
properties  from  chlorine,  being  of  a  deeper  colour,  and  having  an 
odour  somewhat  resembling  that  of  burnt  sugar.    WTater  dissolves 
about  ten  times  its  volume  of  this  gas,  which  imparts  to  the  liquid 
its  peculiar  smell  and  colour.     It  does  not  act  upon  mercury. 

In  what  other  manner  may  it  be  procured  ? 

What  proportion  of  it  is  absorbed  by  water  at  ordinary  temperatures  ? 

What  is  the  specific  gravity  of  this  gas  compared  with  common  air? 

What  peculiar  phenomena  attend  the  immersion  of  metals  in  this  gas  ? 

What  compound  does  it  form  with  oxygen? 

How  is  euchlorine  obtained  ? 

What  are  its  peculiar  properties  ? 

*  See  Scientific  Class  Book,  pt.  i.  pp.  154,  155,  for  the  specific  gravities 
of  several  of  the  gases  relatively  to  that  of  water. 


80  CHEMISTRY. 

Vegetable  colours  in  general  are  destroyed  when  exposed  to  it, 
some  of  the  blues  becoming  reddened  before  the  tint  is  obliterated. 
When  it  is  detonated  with  hydrogen,  by  passing  through  the  mix- 
ture of  these  gases  the  electric  spark,  it  becomes  decomposed, 
forming  water  and  muriatic  acid. 

182.  Peroxide  of  chlorine  is  a  compound  of  one  equivalent  of 
chlorine  and  four  of  oxygen  (or  36  Ch.  -f-  32  Ox.)  It  is  a  gaseous 
body,  which  may  be  procured  by  mixing  50  or  GO  grains  of  chlo- 
rate of  potash  with  a  small  quantity  of  concentrated  sulphuric 
acid,  so  as  to  form  a  paste,  and  exposing  it  in  a  small  retort  to  the 
heat  of  a  water-bath,  which  must  be  carefully  kept  below  the 
boiling  point.  The  gas  which  is  evolved,  when  collected  over 
mercury,  exhibits  a  deeper  colour  and  a  more  aromatic  odour  than 
the  protoxide.  It  is  rapidly  absorbed  by  water,  forming  a  yellow 
solution,  with  a  strongly  astringent,  disagreeable  taste,  but  no 
acidity.  It  bleaches  vegetable  blues,  without  reddening  them. 
When  heated,  it  explodes  violently,  at  a  temperature  above  114°, 
with  an  increase  of  volume  amounting  to  one-half,  oxygen  and 
chlorine  gases  being  produced.  Mr.  Faraday  succeeded  in  con- 
densing this  gas  to  the  liquid  state,  by  exposing  it  to  pressure  at 
a  temperature  32°  below  the  freezing-point  of  water.  Peroxide 
of  chlorine  was  discovered  by  Sir  H.  Davy  in  1815,  and  about 
the  same  time  by  Count  Von  Stadion. 

183.  Chloric  acid  is  that  compound  which  enters  into  combina- 
tion with  potash  to  form  the  chlorate  of  potash,  already  men- 
tioned. This  acid  may  be  produced  by  passing  a  current  of 
chlorine  gas  through  a  mixture  of  oxide  of  silver  and  water,  part  of 
the  chlorine  combining  with  the  metal  to  form  chloride  of  silver, 
and  part  uniting  with  the  oxygen  of  the  decomposed  oxide  to 
constitute  the  chloric  acid.  The  chloride,  which  is  insoluble,  is 
then  to  be  separated  by  filtering,  and  the  excess  of  chlorine  con- 
tained in  the  liquid  being  expelled  by  heat,  the  acid  will  be  ob- 
tained in  the  state  of  an  aqueous  solution.  Chlorate  of  barytes, 
when  decomposed  by  sulphuric  acid,  also  yields  chloric  acid. 
When  concentrated  by  evaporation,  this  acid  is  an  oily  fluid,  trans- 
parent, colourless,  and  having  a  sour,  astringent  taste ;  reddening 
vegetable  blues,  and  uniting  with  various  bases  to  form  salts.  It 
is  decomposed  by  the  muriatic  and  sulphurous  acids,  and  also  by 
the  hydrosulphuric  or  sulphuretted  hydrogen ;  but  not  by  those 
acids  which  contain  large  proportions  of  oxygen.  It  appears  to 
be  composed  of  one  atom  of  chlorine  and  five  of  oxygen  (36 
Ch.  +  40  Ox.) 

What  effect  has  euchlorine  on  vegetable  colours  ? 

In  what  state  is  the  peroxide  of  chlorine  found  to  exist? 

How  is  it  procured  ? 

What  are  its  properties  ? 

By  whom  was  it  discovered  ? 

How  is  chloric  acid  produced  ? 

What  is  its  state  when  concentrated  ? 

What  acid  properties  does  it  exhibit  ? 

What  is  its  composition? 


IODINE.  81 

184.  Perchloric  acid,  discovered  by  Count  Von  Stadion,  proba- 
bly consists  of  one  equivalent  of  chlorine  with  seven  of  oxygen  ; 
but  its  constitution  and  properties  have  not  yet  been  accurately 
investigated.    It  has  been  obtained  in  the  form  of  a  dense,  colour- 
less liquid,  in  which  it  is  united  with  water,  neither  this  nor  the 
chloric  acid  apparently  being  capable  of  existing  in  an  insulated 
state. 

185.  Chlorine  forms  a  combination  with  water,  which  has  been 
termed  hydrate  of  chlorine.     If  a  small  quantity  of  water  be  intro- 
duced into  a  retort  or  bottle  with  chlorine  gas,  and  the  vessel  be 
kept  a  few  days  in  a  dark  place,  where  the  temperature  does  not 
rise  above  the  freezing  point,  this  compound  will  be  obtained  in 
the  state  of  a  mass  of  prismatic  and  acicular  crystals,  with  water 
adhering,  which  may  be  separated  by  blotting-paper,  previously 
cooled  to  prevent  the  crystals  from  melting. 

186.  The  crystalline  hydrate  is  of  a  pale  yellow  colour,  and 
very  volatile.    If  a  small  portion  of  these  crystals,  carefully  dried, 
be  introduced  into  a  bent  tube,  as  in  the  annexed  figure,  the  hy- 
drate may  be  sublimed  by  applying  a  gentle  heat  to  one  end,  and 

at  the  same  time  cooling  the 
33  other.  Thus  if  the  extremity 
of  the  tube  A,  in  which  the 
crystals  are  contained,  is  im- 
mersed in  water  heated  at  about  90°,  they  will  be  decomposed, 
forming  two  distinct  fluids,  the  upper  consisting  of  a  saturated 
solution  of  chlorine  in  water,  and  the  lower  of  condensed  chlo- 
rine, in  the  state  of  a  dark^oily  body.  When  the  other  extremity 
of  the  tube,  B,  is  cooled,  the  chlorine  will  distil  over.  If  the 
tube  be  again  cooled  to  70°,  the  chlorine  and  water  will  reunite 
to  form  fresh  crystals. 

Iodine. 

187.  This  substance  was  first  discovered  in  kelp,  or  the  coarse 
alkaline  matter  procured  from  the  ashes  of  marine  plants.     In  its 
chemical  properties,  it  resembles  chlorine  and  bromine  ;  and,  like 
those  bodies,  it  is  supposed  to  be  an  elementary  Substance,  having 
never  yet  been  decomposed.     The  name  iodine  was  given  it  by 
M.  Gay  Lussac,  in  allusion  to  its  colour*  when  in  the  state  of  gas. 

188.  Iodine  may  be  procured  by  various  processes.     After  the 
extraction  of  soda  from  kelp  for  the  use  of  the  soap-boilers,  a 

By  whom  was  perchloric  acid  discovered  ? 

In  what  form  does  it  exist? 

What  is  the  composition  of  the  hydrate  of  chlorine  ? 

How  is  it  produced  \ 

How  may  it  be  exhibited  in  a  solid  crystalline  form  ? 

How  is  the  hydrate  decomposed  ? 

From  what  substance  was  iodine  first  procured  ? 

Which  of  the  other  non-metallic  bodies  does  it  most  nearly  rr>~emble  ? 

*  From  the  Greek,  'Iw<fy?,  like  a  violet. 


.82  CHEMISTRY. 

brown  liquid  remains,  which  must  be  subjected  to  a  heat  of  about 
230°,  then  saturated  with  sulphuric  acid,  diluted  with  its  own 
bulk  of  water,  and  pouring  off  the  liquor  when  cold  from  the 
crystals  which  will  be  formed,  consisting  chiefly  of  sulphate  of 
soda,  it  is  to  be  filtered,  and  to  every  twelve  ounces  must  be  added 
1000  grains  of  black  oxide  of  manganese  in  powder;  this  mixture 
being  put  into  a  glass  globe,  or  large  matrass,  to  which  another  is 
to  be  adapted  ;  the  former  must  be  heated  with  charcoal,  and  the 
iodine  will  then  pass  over,  in  beautiful  violet-coloured  vapours, 
which  will  be  condensed  in  crystalline  plates,  having  the  colour 
and  lustre  of  plumbago. 

189.  Iodine  thus  obtained  is,  at  the  ordinary  temperature  of  the 
atmosphere,  a  soft,  friable  solid,  which  may  be  easily  reduced  to 
a  fine  powder.  Its  specific  gravity  is  4.946.  It  differs  from  metals 
in  being  a  non-conductor  of  electricity.     If  passed  through  a  red- 
hot  tube,  either  alone  or  over  charcoal,  it  undergoes  no  change. 
Applied  to  the  skin,  it  occasions  a  yellow  stain  ;  and  it  has  a  hot, 
acrid  taste,  and  an  odour  resembling  that  of    diluted  chlorine. 
Taken  internally  in  a  considerable  quantity,  it  is  poisonous,  but  it 
has  been  used  in  medicine  in  small  doses  ;  and  there  is  reason  to 
believe,  that  burnt  sponge,  employed  as  a  remedy  for  bronchocele, 
owes  its  efficacy  to  the  iodine  which  it  contains. 

190.  Iodine  is  very  volatile,  rising  in  vapour  at  a  temperature 
of  from  60°  to  80°,  and  very  freely  at  higher  temperatures,  boiling 
rapidly  at  350°.     Its  specific  gravity,  in  the  gaseous  state,  is  to 
that  of  atmospheric  air  as  8.7011  to  1 ;  so  that  it  is  by  much  the 
heaviest  of  all  elastic  fluids  yet  known.  This  vapour  is  124  times 
the  weight  of  hydrogen,  and  as  it  combines  with  that  body  in 
equal  volumes,  the  number  124  has  been  taken  as  the  equivalent 
or  combining  weight  of  iodine.     It  renders  vegetable  colours  yel- 
low, and  forms  with  water  a  yellow  solution,  though   but  a  very 
minute  portion  of  it  is  taken  up  by  that  fluid.     It  is  much  more 
soluble  in  ether  or  spirit  of  wine,  with  which  it  forms  deep-brown 
solutions.     This  substance  has  the  peculiar  property  of  forming 
with  starch  an  insoluble  compound  of  a  deep  blue  or  violet  colour; 
and  hence  starch  has  been  used  with  advantange  as  a  delicate  test 
of  the  presence  of  iodine. 

191.  With  oxygen  iodine  enters  into  combination,  forming  lodic 
or  oxiodic  add.     This  acid  may  be  produced  by  adding  chlorate  of 
potash  and  hydrochloric  or  muriatic  acid  to  iodine;  and  exposing 

Describe  the  process  for  procuring  iodine  from  kelp. 

What  are  its  ordinary  sensible  properties  ? 

What  is  its  specific  gravity  ? 

How  does  it  differ  from  metals  ? 

To  what  useful  purpose  may  it  be  subservient  ? 

At  what  temperature  is  it  converted  from  the  solid  to  the  aeriform  state? 

What  is  its  specific  gravity  in  the  latter  state  ? 

What  is  its  combining  atomic  weight  ? 

What  peculiar  effect  has  it  on  starch  ? 

What  are  its  compounds  with  oxygen  ? 


BROMINE,  83 

the  mixture  to  a  gentle  heat,  two  new  compounds  will  thus  be 
formed,  namely,  chloriodic  acid  and  oxiodic  acid.  By  the  appli- 
cation of  greater  heat,  the  former  may  be  driven  off,  and  the  oxiodic 
acid  will  be  left  pure.  The  oxygenation  of  iodine  may  be  also  ef- 
fected by  heating  that  substance  repeatedly  in  nitric  acid.  The 
iodic  acid  is  a  white,  semi-transparent,  deliquescent  solid,  having 
a  sour  taste,  but  no  smell.  Its  specific  gravity  exceeds  2,  and  it 
consists  of  1  proportional  of  iodine,  and  5  of  oxygen,  so  that  its 
equivalent  number  is  124  -j-  40  =  161.  Its  aqueous  solution  red- 
dens, and  then  destroys  vegetable  colours.  When  mixed  with 
charcoal,  sugar,  sulphur,  and  other  combustible  substances,  it 
detonates  on  the  application  of  heat. 

192.  It  has  been  stated,  that  the  solution  of  this  acid  corrodes 
all  the  metals,  and  even  acts  on  gold  and  platina;  but  Mr.  Con- 
nell,  who  procured  it  by  means  of  the  nitric  acid,  confirms  the 
observation  of  Serullas,  that  it  does  not  attack  gold  ;  and  adds, 
that  it  is  equally  inert  with  respect  to  platina,  and  that  iron  filings 
thrown  into  the  acid  solution  caused  no  effervescence;  but  when 
the  liquid  was  boiled,  a  white  powder  was  precipitated.* 

193.  Iodine  is  capable  of  union  with  chlorine,  forming  a  com- 
pound called  chloriodic  acid,  discovered  about  the  same  time  by 
Sir  H.  Davy  and  M.  Gay  Lussac.     This  acid  makes  its  appear- 
ance, as  already  stated,  during  the  process  for  obtaining  iodic  acid 
from  chlorate  of  potash  and  muriatic  acid  ;  but  it  may  be  procured 
from  the  direct  union  of  its  constituents.     Thus  on  passing  a  cur- 
rent of  chlorine  gas  into  a  vessel  containing  iodine,  the  gas  is 
quickly  absorbed ;  and  the  result  will  be  a  substance,  colourless 
when  the  two  bodies  combine  in  proper  proportions,  red  or  brown 
when  there  is  an  excess  of  iodine,  and  yellow  if  there  be  an  excess 
of  chlorine.     It  is  volatile,  and  may  be  sublimed  without  decom- 
position.    It  is  deliquescent,  and  dissolves  readily  in  water,  form- 
ing an  acid  solution,  which  destroys  vegetable  blues.     The  salifia- 
ble  bases,  when  presented  to  this  acid,  in  solution,  decompose  it, 
and  iodic  and  muriatic  acids  are  produced.     It  is  said  likewise  to 
be  decomposed  by  mercury. 

Bromine. 

/  194.  This  is  among  the  most  recently  discovered  of  the  simple 
substances.  It  is  commonly  procured  from  the  uncrystallizable 
liquid  called  bittern,  which  remains  after  the  manufacture  of  sea- 
How  is  oxiodic  acid  formed  ? 

What  are  the  properties  of  this  acid  ? 

What  is  its  composition  ? 

What  compound  does  iodine  form  with  chlorine  ? 

By  whom  was  that  compound  discovered  ? 

How  is  it  obtained  ? 

What  sensible  properties  does  it  possess 

*  See  Jameson's  Journal  of  Science  for  1831. 


84  '  CHEMISTRY. 

salt.  If  a  current  of  chlorine  gas  be  passed  through  this  liquid, 
it  assumes  an  orange  tint,  and  yields  a  peculiar  disagreeable 
smell,  arising  from  -the  evolution  of  bromine  ;*  a  portion  of 
sulphuric  ether  is  then  to  be  agitated  with  it,  and  on  being  allowed 
'to  stand,  it  will  separate  from  the  water,  together  with  the  bromine, 
which  gives  it  a  reddish-brown  colour.  The  ethereal  solution 
must  be  shaken  with  a  solution  of  caustic  potash,  when  bromate 
of  potassa  and  bromide  of  potassium  will  both  be  formed.  The 
latter  of  these  salts  being  obtained  in  cubic  crystals  by  evaporation, 
is  to  be  decomposed  by  a  solution  of  chlorine  in  water  ;  and  the 
bromine,  which  is  volatile,  may  be  separated  by  distillation,  and 
obtained  in  a  receiver,  kept  cool  by  covering  it  with  ice. 

195.  At  common  temperatures  bromine  is  a  liquid ;  at  about  10° 
below  zero,  Fahrenheit,  it  becomes  congealed  into  a  crystalline, 
foliated  mass;  and  at  116°  it  boils.     It  is  about  three  times  the 
weight  of  water.     The  liquid  has  a  deep,  dull,  red  colour,f  and  a 
peculiarly  unpleasant   suffocating  odour;    and  its  taste  is  also 
strong  and  nauseous.     It  corrodes  the  skin,  and  stains  it  of  a  yellow 
colour;  and  it-must  also  be  remarked,  that  it  is  a  powerful  and 

•  dangerous  poison.  It  dissolves  but  sparingly  in  water,  more  easily 
in  alcohol,  and  most  readily  in  ether.  Vegetable  colours,  as  lit- 
mus, and  even  indigo,  are  destroyed  by  it.  A  burning  taper  plunged 
in  its  vapour  quickly  becomes  extinguished,  the  flame  previously 
assuming  a  reddish  tint.  Phosphorus  inflames  spontaneously  in 
its  vapour.  Tin  and  antimony  likewise  take  fire  in  it ;  and  potas- 
sium introduced  into  it  explodes  with  violence.  In  its  general 
mode  of  action  it  resembles  chlorine  and  iodine,  being  reckoned 
a  supporter  of  combustion. 

196.  With  oxygen  it  forms  a  compound   called  bromic  acid, 
which  may  be  obtained  by  adding  sulphuric  acid  to  the  combina- 
tion of  this  acid  with  barytes  (bromate  of  barytes  ;)  and  sulphate 
of  barytes  being  thus  formed,  when  the  whole  of  that  salt  is  pre- 
cipitated, the  bromic  acid  will  remain  in  solution,  and  may  be 
concentrated  by  slow  evaporation.  It  cannot,  however,  be  entirely 
deprived  of  water,  as  it  is  partially  decomposed  at  a  high  tempera- 
ture.    The  acid  solution  has  very  little  smell,  but  possesses  a 
sour  taste,  and  it  first  reddens  and  then  destroys  the  blue  colour 
of  litmus. 

From  what  source  is  bromine  obtained  ? 

By  what  process  is  it  procured  ? 

In  what  state  does  it  exist  at  common  temperatures  ? 

At  what  temperatures  does  it  change  its  forms  ? 

What  power  does  it  possess  in  respect  to  combustion  ? 

What  effect  has  its  vapour  on  the  metals  ? 

What  compound  is  formed  by  bromine  and  oxygen  ? 

*  Bromine  derives  its  appellation  from  its  nauseous  flavour,  Bpw/xoj,  its 
Greek  etymon,  signifying  a  stench. 

t  "  Liquid  bromine,  when  viewed  in  thin  portions  or  small  drops,  dis- 
plays a  hyacinthine  red  hue  (red  with  a  tinge  of  yellow ;)  in  larger  masses, 
the  colour  becomes  so  intense  that  it  appears  opaque  and  black." — Milscher- 
Kchs's  Inlrod.  to  Chem.,  vol.  i.  p.  70. 


FLUORINE.  85 

197.  The  specific  gravity  of  the  vapour  of  bromine  and  its 
atomic  weight,  are  uncertain,  being  variously  stated  by  different 
experimentalists.     According  to  Berzelius,  the  combining  weight 
of  this  body  is  78.26;  but  75  is  the  number  generally  adopted. 
Hence  bromic  acid,  containing  1  atom  of  bromine  with  5  of  oxygen, 
its  equivalent  number  will  be  75  -\-  40  =  115. 

198.  Bromine  unites  with  chlorine,  when  a  current  of  the  latter 
is  passed  through  the  liquid  bromine,  and  the  vapours  which  arise 
at  a  low  temperature  may  be  obtained  by  condensation  in  the  form 
of  a  reddish-yellow  liquid  called  chloride  of  bromine.  It  has  a  very 
penetrating  odour,  and  disagreeable  taste.  It  is  extremely  volatile  ; 
and  metals  reduced  to  fine  powder  take  fire  in  its  vapour.     The 
solution  of  chloride  of  bromine  in  water  acts  powerfully  in  bleach- 
ing vegetable  substances. 

199.  Bromine  unites  also  with  iodine,  hydrogen,  sulphur,  phos- 
phorus, and  selenium  ;  as  well  as  with  many  of  the  metals,  form- 
ing compounds  called  bromides. 

Fluorine. 

200.  This  body,  though  from  the  analogy  of  its  mode  of  action, 
when  in  combination  with  other  substances,  to  that  of  oxygen  and 
chlorine,  it  is  supposed,  like  them,  to  be  a  simple  or  elementary 
body,  has  yet  never  been  obtained  in  a  separate  state,  on  account 
of  the  difficulty,  or  rather  impossiblity,  of  keeping  it  uncombined 
in  vessels  of  any  known  substance  whatever.     Its  compounds  are 
not  of  common  occurrence,  except  the  mineral  called  fluor  spar, 
which  appears  to  be  a  compound  of  fluorine  with  calcium,  or  the 
metal  of  lime;  and  it  only  occurs  in  a  few  other  mineral  sub- 
stances. 

201.  The  fluoride  of  calcium  (fluorspar)  maybe  decomposed 
without  difficulty;  but  the  fluorine  is  no  sooner  extricated,  than 
it  enters  into  union  with  some  other  body.   One  of  the  compounds 
which  it  readily  forms  is  with  hydrogen,  constituting  hydrofluoric 
acid,  which  may  be  thus  prociired  :  Let  fluor  spar,  finely  powdered, 
and  mixed  with  twice  its  weight  of  strong  liquid  sulphuric  acid, 
be  distilled  by  a  moderate  heat  in  a  silver  or  leaden  retort,  to 
which  should  be  adapted  a  silver  tube  and  receiver,  the  latter  of 
which  must  be  kept  cool  during  the  operation,  by  immersing  it  in 
a  mixture  of  pounded  ice  or  snow,  and  salt.    The  hydrofluoric  acid 
will  then  pass  over  in  the  form  of  a  very  volatile  liquid,  but  having 
the  appearance  of  sulphuric  acid.     It  is  best  preserved  in  bottles 
of  silver  or  lead,  with  well-fitted  stoppers  of  the  same  metal.     Its 

What  is  the  combining  weight  of  bromine  ? 
How  many  atoms  of  each  ingredient  enter  into  bromic  acid  ? 
In  what  manner  can  bromine  be  united  with  chlorine  ? 
What  is  the  compound  called  ? 

What  difficulty  opposes  the  analytical  investigation  of  the  properties  of 
fluorine  ? 

From  what  substance  may  fluorine  be  disengaged  ? 
How  may  hydrofluocir  acid  be  received  and  preserved  ? 
H 


86  CHEMISTRY. 

specific  gravity  is  1.06,  but  it  becomes  increased  in  density  by  the 
addition  of  water  to  1.25,  affording  a  singular  instance  of  fluid 
condensation.  It  has  a  strong  attraction  for  water,  beyond  that  of 
sulphuric  acid  ;  and  great  heat  is  evolved  when  it  is  dropped  <nto 
water.  As  it  is  extremely  volatile,  the  utmost  care  should  be 
taken  in  making  experiments,  to  avoid  inhaling  its  vapour,  the 
irritating  effects  of  which  are  extremely  injurious ;  and  the  liquid 
acid  itself  acts  as  a  powerful  caustic  when  dropped  on  the 
skin. 

202.  Among  the  most  curious  and  important  properties  of  this 
acid  is  its  action  on  glass,  which  it  deeply  corrodes,  in  consequence 
of  its  affinity  for  the  basis  of  the  siliceous  earth  contained  in  the 
glass,  with  which  it  forms  a  new  compound  called  silicofluoric 
acid.     Thus  it  decomposes  glass,  and  hence  destroys  the  trans- 
parency of  glass  vessels  or  plates  with  which  it  comes  in  contact. 
This  property  of  the  acid  has  been  ingeniously  applied  to  the  pur- 
pose of  making  engravings  or  etchings  on  glass.     These  are  exe- 
cuted in  a  manner  analogous  to  etchings  on  copper  with  aqua  fortis. 
Plates  of  glass,   coated   with  bees'  wax  and  turpentine  melted 
together,  may  have  figures  traced  on  them  with  an  etching  needle  ; 
after  which  they  may  be  covered  with  the  diluted  acid,  or  exposed 
to  its  vapour,  when  on  removing  the  coating,  the  figures  will  be 
found  delineated  on  the  glass. 

203.  Attempts  have  been  made  to  procure  fluorine  in  a  separate 
state,  by  decomposing  its  compounds  by  means  of  Galvanism,  or 
by  the  more  usual  operations  of  chemical  analysis  :  and  in  both 
cases  the  object  has  been  frustrated  by  the  impossibility  of  pre- 
venting the  nascent  element  from  forming  immediately  new  com- 
pounds.    When  hydrofluoric  acid  is  acted  on  by  a  Galvanic  pile, 
inflammable  gas  will  be  given  off  at  the  wire  connected  with  the 
negative  pole,  and  the  opposite  wire  of  platina  will  become  cor- 
roded and  covered  with  a  chocolate-coloured  powder,  which  ap- 
pears to  be  fluoride  of  platina. 

204.  The  combination  of  fluorine  with  silver  (fluoride  of  silver) 
may  be  decomposed   by  means  of  chlorine,  which  unites  with 
the  silver ;  but  the  fluorine  cannot  thus  be  obtained  in  a  separate 
state.     For  when  fluoride  of  silver  is  placed  in  a  glass  retort,  and 
chlorine  is  added,  the  fluorine  will  be  extricated  ;   but  it  imme- 
diately decomposes  the  siliceous  earth  of  the  glass,  and  enters 
into  union  with  its  basis  called  silicon,  with  which  it  forms  silico- 
fluoric  acid.    If  the  decomposition  be  effected  in  a  vessel  of  platina, 
fluoride   of  platina,  the   substance   already   mentioned,  will   be 
formed  ;  and  if  a  retort  of  lead  or  any  other  metal  be  used,  the 

What  is  its  specific  gravity  ? 

What  precautions  are  necessary  in  experiments  with  this  gas  ? 

What  is  the  nature  of  the  action  of  fluoric  acid  on  glass  ? 

What  compound  results  from  this  action  ? 

Why  cannot  fluorine  be  separately  obtained  ? 

What  occurs  in  decomposing  hydrofluoric  acid  by  Galvanism? 

Why  may  we  not  obtain  fluorine  from  fluoride  of  silver  ? 


HYDROGEN.  87 

fluorine  will  combine  with  it,  unless  water  be  present,  which  it 
decomposes  to  form  hydrofluoric  acid,  previously  described. 

205.  Besides  the  compounds  already  mentioned,  fluorine  unites 
with  boron,  the  basis  of  boracic  acid,  with  which  it  constitutes 
borofiuoric  acid,  or  as  it  has  been  also  called,  fluoride  of  boron. 
It  also  unites  with  sulphur  and  phosphorus;  but  these  compounds 
have  been  but  lately  discovered.     No  combinations  have  yet  been 
obtained  of  fluorine  with  oxygen,  chlorine,  iodine,  bromine,  carbon, 
or  nitrogen. 

Hydrogen. 

206.  Hydrogen  is  one  of  the  most  important  among  the  inflam- 
mable substances,  being  abundantly  diffused  throughout  nature  in. 
various  states  of  combination.     Its  distinct  existence  as  a  peculiar 
kind  of  matter,  was  first  ascertained  by  Mr.  Cavendish,  in  1766. 
The  specific  gravity  of  hydrogen  gas  being  less  than  that  of  any 
other  substance  with  which  we  are  acquainted,  it  seems  to  possess 
a  strong  claim  to  the  title  of  a  simple  or  uncompounded  body. 
The  weight  of  100  cubic  inches  of  hydrogen  gas  is  less  than  three 
grains,  while  the  same  bulk  of  atmospheric  air  will  weigh  30^ 
grains.     The  comparative  levity  of  this  elastic  fluid  gave  rise  to 
its  employment  for  the  inflation  of  air-balloons. 

207.  Hydrogen  gas,  when  pure,  is  perfectly  transparent.    It  is, 
however,  usually  mixed  with  certain  adventitious  matters,  which 
communicate  to  it  a  very  unpleasant  smell,  but  when  these  are 
separated,  it  appears  to  be  completely  inodorous.    It  possesses  no 
taste.     Hydrogen  gas  will  not  serve  for  the  respiration  of  animals, 
though  it  does  not,  like  some  gases,  prove  immediately  deleterious 
to  those  who  breathe  it;  and  when  largely  mingled  with  atmos- 
pheric air,  it  may  be  respired  with  safety.     Vegetables  grow  and 
flourish  when  confined  in  this  gas. 

208.  Hydrogen  gas  is  extremely  inflammable,  readily  burning 
when  in  contact  with  oxygen  gas  or  atmospheric  air.     The  pro- 
duce of  this  combustion  is  water,  which  is  formed  and  decomposed 
by  many  processes,  natural  and  artificial. 

20i).  The  most  usual  method  of  obtaining  hydrogen  gas  for  the 
inflation  of  balloons,  or  for  chemical  experiments,  is  by  adding  sul- 
phuric acid  to  a  mixture  of  zinc,  or  iron  filings  or  scraps,  with  water. 
The  metal  in  this  case,  assisted  by  the  acid,  attracts  the  oxygen 
of  the  water,  and  its  hydrogen  is  set  free,  and  may  be  collected 
for  use  by  means  of  a  proper  apparatus.  Hydrogen  gas  may  be 
also  procured  from  water  by  electricity.  Thus  water  inclosed  in 
a  glass  tube,  may  be  decomposed  by  passing  through  it  a  current 
of  electric  sparks.  It  may  also  be  separated  into  its  constituent 
parts  by  exposing  it  to  the  action  of  a  Galvanic  battery.* 

With  what  other  materials  does  fluorine  combine  ? 

How  early  was  hydrogen  discovered  ?     What  are  its  sensible  properties  ? 

What  is  its  'influence  on  respiration  and  on  vegetation? 

What  is  the  product  of  its  combustion  in  oxygen? 

How  is  hydrogen  obtained  by  aeronauts  ? 

*  See  above  No.  91. 


88  CHEMISTRY. 

210.  Though  hydrogen  may  be  made  to  burn  when  mixed  with 
oxygen,  atmospheric  air,  and  other  supporters  of  combustion,  it 
extinguishes  a  lighted  taper,  or  any  burning  body  immersed  in  it. 
It  may,  as  already  stated,  be  breathed  with  safety  for  a  short  time, 
though  it  will  not  support  animal  life.     If  the  lungs  be  filled  with 
it  by  inhaling  a  few  times  this  gas  from  a  bladder,  or  a  bag  of 
oiled  silk,  a  peculiar  effect  is  produced  on  the  voice,  which  is 
rendered   much   shriller   than   usual,   bat   its   influence   is   only 
temporary.* 

211.  Protoxide  of  hydrogen — Hydrogen  combines  with  several 
other  simple  substances,  and  especially  with  the  supporters  of 
combustion,  forming  many  important  compounds.     With  oxygen 
it  is  found  to  unite  in  two  proportions.     When  two  volumes,  or 
parts  by  measure,  of  hydrogen  gas,  are  mixed  with  one  volume, 
or  measure,  of  pure  oxygen  gas,  in  a  glass  globe,  or  any  other  re- 
ceptacle previously  exhausted  of  air,  the  gases  being  inflamed  by 
the  electric  spark,  will  combine  with  the  extrication  of  light  and 
heat ;  and  the  interior  of  the  globe  will  become  lined  with  drops 
like  dew,  which  being  collected   and  weighed,  will  be  found  to 
consist  of  pure  water,  equal  in  weight  to  that  of  the  gases  which 
have  disappeared.     There  are  many  modes  of  making  this  experi- 
ment, among  which  may  be  mentioned  the  following,  as  being 
easily  practicable,  with  the  assistance  of  an  electrical  machine  : 


/ . .— — • 

212.  A  very  large  bladder,  A,  is  to  be  filled  with  oxygen  and  hy- 
drogen gases,  in  the  proportions  just  mentioned.  To  the  opening 
must  be  fitted  a  sound  cork,  B,  with  a  short  glass  tube  passed 
through  it,  by  means  of  which  the  gases  may  be  introduced  into  it ; 
and  on  each  side  of  the  tube  brass  wires  are  to  be  passed  through 
the  cork,  so  that  their  ends  may  project  a  little  way  within  the 
bladder  at  C,  where  they  are  to  be  brought  within  about  a  quarter 

What  is  its  effect  on  a  burning  body  wholly  immersed  in  it? 
What  effect  has  it  on  the  voice  when  inhaled  ? 
By  what  chemical  name  should  water  be  designated  ? 
Describe  the  apparatus  for  producing  water  by  the  help  of  ele< 

*  This  effect,  is  explained  on  the  principle  advanced  by  Laplace  and  ex- 
perimentally applied  by  Dulong,  that  the  shrillness  of  tones  produced  by 
different  eases  depends  on  their  specific  heat.     And  though  several  obser- 
vations, recently  published,  of  facts,  showing  the  diminution  of  power  and 
alteration  of  tone  in  the  human  voice  on  high  mountains,  seem  to  indicate, 
that  the  specific  gravity  of  the  air,  or  of  a  gas,  has  an  important  influence 
in  determining  the  acuteness  of  its  tone  ;  yet,  it  will  be  probablj 
able  with  the  theory  of  Laplace,  when  we  consider  that  the  specil 
of  air  is  incrrased  by  the  increase  of  its  bulk.— See  Silliman  s  Journal,  vol. 
28,  p.  226.— Ed. 


HYDROGEN. 


89 


of  an  inch  of  each  other.  To  the  ends  of  the  wires  without  the 
bladder,  are  to  be  attached  two  other  wires,  D  E,  from  twenty  to 
thirty  feet  in  length.  One  of  these  wires,  D,  is  to  be  brought  in. 
contact  with  the  outside  of  an  electrical  jar ;  and  the  other  wire, 
E,  to  be  advanced  within  an  inch  of  the  brass  knob,  F,  of  the  same 
jar;  then  on  charging  the  jar  by  means  of  an  electrical  machine, 
when  it  has  been  sufficiently  excited,  a  discharge  will  take  place, 
the  spark  passing  from  the  knob,  F,  through  the  wire,  E,  and 
another  spark  will  pass  between  the  wires  within  the  bladder  at 
C,  which  will  occasion  an  explosion  of  the  gases,  and  the  produc- 
tion of  water,  which  however  will  be  liable  to  be  dissipated  by 
the  bursting  of  the  bladder. 

213.  If  there  be  an  excess,  in  the  mixture,  of  either  of  the  gases, 
they  will  still  only  unite  in  the  ratio  already  stated,  and  the  super- 
fluous gas  will  remain  in  an  uncombined  state.  The  production 
of  water  by  the  union  of  oxygen  and  hydrogen  gases,  may  be  ex- 
hibited by  simply  burning  a  jet  of  hydrogen  gas,  from  a  bladder 
with  a  stop-cock,  under  a  bell-glass,  including  atmospheric  air; 
and,  as  the  combustion  proceeds,  water  will  be  formed,  which 
condensing  on  the  inner  surface  of  the  glass,  will  trickle  down  its 
sides. 

214.  The  accompanying  figure  re- 
presents a  cheap  and  convenient  ap- 
paratus for  the  production  of  hydrogen 
gas.     A  glass  phial,  A,  holding  from 
a  pint  to  a  quart,  or  more,  has  one  or 
two  holes,  a  quarter  of  an  inch  in  dia- 
meter, perforated  in  the  bottom.      A 
quantity  of  fragments  of  glass,  B,  too 
lar/yo  to  pass  through  the  holes,  are 
put  into  the  phial,  covering  the  bottom 
one  half  or  three  quarters  of  an  inch 
in  depth.     On  this,  a  layer  of  frag- 
ments or  clippings  of  zinc,  Z,  is  laid  to 
about  the  same  depth.  A  cork  or  brass 
plug,   C,  with  a  stop-cock  and  pipe 
is  then  fixed,  by  cement  or  wax,  to  the 
mouth  of  the  bottle,  and  the  apparatus 
is  ready  for  use. 

215.  Opening  the   stop-cock,  and 
plunging  the  bottle  in  its  erect  posi- 
tion into  a  solution  of  sulphuric  acid 
in   *vater,    contained   in  any  suitable 
vessel,  the   liquid  rises  through  the 
holes  in  the  bottom,  expels  the  atmos- 
pheric air,  and  fills  the  phial.     Action 

In  what  proportions,  by  bulk  must  the  two  gases  be  mixed  in  order  to  the 
success  of  this  experiment?  Describe  the  apparatus  for  the  generation  ot 
hydrogen  gas  from  zinc  and  sulphuric  acid  ? 

H  2 


90 


CHEMISTRY. 


on  the  zinc  soon  becomes  very  vigorous,  and  if  the  stop-cock  be 
now  closed,  the  upper  part  of  the  vessel  will  soon  be  filled,  the 
generation  of  gas  will  proceed  until  the  acid  has  been  driven  down 
through  the  holes,  below  the  surface  of  the  stratum  of  broken 
glass,  when  it  ceases,  until  some  portion  of  the  gas  is  let  out,  when 
the  acid  will  follow  by  its  hydrostatic  pressure,  and  generate  anew 
portion  to  supply  the  deficiency. 

216.  The  composition  of  water  is  shown  by  analysis,  in  the 
experiments  already  mentioned  relative  to  the  production  of  hy- 
drogen gas. 


Water  may  also  be  decomposed  in  consequence  of  the  affinity 
of  iron  for  oxygen  at  a  high  temperature.  Let  an  open  gun-barrel, 
C,  in  the  preceding  figure,  be  filled  towards  the  centre  with 
iron  turnings ;  to  one  end  of  it  must  be  luted  a  small  retort,  A, 
containing  water  ;  and  to  the  other  end  a  bent  tube,  F,  terminat- 
ing under  a  gas-holder,  or  an  inverted  glass  jar,  filled  with  water, 
G.  The  gun-barrel  passing  across  a  furnace,  or  a  large  chafing-dish, 
is  to  be  heated  by  means  of  charcoal ;  and  when  it  is  red-hot, 
the  water  of  the  retort  must  he  made  to  boil,  by  placing  under  it 
a  small  lamp,  and  the  steam  passing-  over  the  red-hot  iron  will  be 
decomposed  ;  its  oxygen  will  unite  wn^  the  iron,  and  the  hydro- 
gen thus  set  free,  will  pass  through  the  tube,  E,  and  be  collected 
under  the  bell-glass,  G. 

217.  If  this  experiment  be  carefully  made,  by  using  a  compact 
porcelain  or  glass-tube,  instead  of  the  gun-barrel,  and  weighing 
the  iron  before  and  after  the  operation,  it  will  be  found  to  have 
gained  exactly  as  much  as,  added  to  the  gas  produced,  will  be 
equal  to  the  weight  of  the  water  consumed.    Hence  it  will  appear, 
that  water  consists  of  eight  parts  by  weight  of  oxygen,  and  one  of 
hydrogen. 

218.  Water  may  also  be  decomposed  by  means  of  the  Galvanic  or 
Voltaic  battery,  and  by  various  other  methods :  but  in  whatever 
manner  it  be  examined,  it  will  be  found  to  consist  of  the  same 
proportions,  namely,  one  volume  of  oxygen,  and  two  volumes  of 

How  may  the  composition  of  water  be  shown  by  its  analysis  ? 

In  what  manner  may  the  proportion  of  the  ingredients  thus  obtained  be 
determined  ? 

State  the  relations  both  by  volume  and  weight  of  the  two  ingredients 
thus  procured. 


FORMATION  OF  MURIATIC  ACID.  91 

hydrogen  ;  or  eight  parts  by  weight  of  oxygen  and  one  of  hydrogen. 
Hence  it  follows  that  oxygen  gas  must  be  sixteen  times  the  weight 
of  hydrogen  gas  :  therefore,  this  fluid  may  be  supposed  to  consist 
of  one  atom  of  hydrogen,  having  only  the  eighth  part  of  the  weight 
of  an  atom  of  oxygen,  and  the  combining  number  of  which  will 
therefore  be  1 ;  and  one  atom  of  oxygen,  the  combining  num- 
ber of  which  must  be  8 ;  so  that  the  combining  or  proportional 
number  of  water  will  be  9,  the  sum  of  the  numbers  of  its  consti- 
tuent parts. 

219.  Oxygen  and  hydrogen  will  also  combine  in  the  proportion 
of  equal  bulks  of  each  gas.     This  compound  which  has  been 
called  deutoxide  or  peroxide  of  hydrogen,  was  discovered  in  July, 
1818,  by  M.  Thenard,  who  procured  it  by  the  addition  of  peroxide 
of  baryum  and  muriatic  acid  to  water,  and  afterwards  precipitating 
the  resulting  protoxide  of  baryum  with  sulphuric  acid ;  the  excess 
of  oxygen  in  the  peroxide  entering  into   combination  with   the 
water,  and  thus  converting  it  into  oxygenated  water,  or  peroxide 
of  hydrogen.    But  other  additions  and  repeated  manipulations  are 
requisite  to  separate  the  muriatic  acid  from  the  oxygenated  water, 
and  obtain  the  latter  in  a  pure  state,  the  process  being  altogether 
complicated  and  troublesome.* 

220.  Peroxide  of  hydrogen  thus  prepared,  is  a  colourless  syrup- 
like  substance,  of  the  specific  gravity  of  about  1.45.     It  is  nearly 
destitute  of  smell,  destroys  vegetable  blue  colours,  and  bleaches 
the  skin,  on  which  it  acts  as  a  caustic  when  the  application  is 
continued.     It  rises  in  vapour,  even  at  low  temperatures,  and  can- 
not be  congealed  by  cold.     At  58°  of  Fahrenheit  it  becomes  de- 
composed, oxygen  gas  being  given  off  in  abundance,  and  at  the 
heat  of  boiling  water  it  explodes.    It  is  decomposed  by  all  the 
metals,  except  iron,  tin,  antimony,  and  tellurium.     The  metals 
should  be  powdered,  or  otherwise  finely  divided  ;  and  with  some 
of  them,  as  silver,  gold,  or  platina,  the  decomposition  takes  place 
with  the  evolution  of  light  and  heat. 

221.  Among  the  most  important  compounds  of  hydrogen,  is 
that  which  it  forms  with  chlorine,  constituting  the  powerful  acid 
commonly  called  muriatic  acid,  and  sometimes  hydrochloric  acid. 
Under  the  former  appellation,  it  has  long  been  known,  and  also 
under  that  of  spirit  of  salt,  being  obtained  from  the  decomposition 

What  conclusions  may  we  draw  from  the  facts  thus  developed  in  regard 
to  the  atomic  constitution  of  the  two  gases? 

What  compound  other  than  water  may  be  formed  of  oxygen  and  hydro- 
gen ? 

When  and  by  whom  was  it  discovered  ? 

What  are  the  distinguishing  properties  of  the  peroxide  of  hydrogen  ? 

At  what  temperature  is  it  decomposed  ? 

How  does  it  react  on  silver,  gold,  and  platina  ? 

What  compound  does  hydrogen  form  with  chlorine  ? 

*  For  an  account  of  the  mode  of  obtaining  this  body,  see  Jour,  of  Science, 
ed.  at  ft.  I.,  vol.  iii.  pp.  115 — 120.  Also  Webster's  Manual  of  Chemistry,  on 
the  basis  of  Brande's  p.  267. 


92  CHEMISTRY. 

of  common  or  marine  salt.  In  this  state  it  is  a  liquid,  being  com- 
bined with  water ;  but  it  may  also  be  obtained  alone,  in  the  form 
of  gas,  and  the  mode  of  procuring  it  was  first  described  by  Mr. 
Cavendish,  in  1766. 

222.  It  was  supposed  that  muriatic  acid,  like  the  nitric,  sul- 
phuric, and  many  others,  consisted  of  oxygen  combined  with  some 
acidifiable  base,  and  in  pursuance  of  that  notion  various  attempts 
were  made  to  decompose  it,  all  which  proved  more  or  less  un- 
satisfactory.    At  length  it  was  ascertained,  through  the  experi- 
ments  of  Sir    H.    Davy  in    England,  and  of  Gay  Lussac   and 
Thenard  in  France,  that  muriatic  acid  gas,  when  pure,  may  be 
separated    into   hydrogen   and   chlorine,  and    that   consequently 
oxygen  does  not  enter  into  its  composition.     Hence  it  appears 
that  Scheele — (who   discovered   chlorine,   and    obtained   it,   by 
separating  from  it  the  hydrogen  with  which  it  is  united  in  muria- 
tic acid,  and  which  he  therefore  supposed  to  be  a  compound  of 
hydrogen  with  the  newly-obtained  gas,) — formed  a  correct  con- 
clusion. 

223.  If  chlorine  and  hydrogen  in  equal  quantities  by  measure 
be  mixed  together,  and  exploded  by  the  electric  spark,  or  a  burn- 
ing match,  muriatic  acid  will  be  formed;  and  if  the  experiment  be 
properly  conducted,  the  quantity  of  acid,  or  compound  gas  obtain- 
ed, will   be  equal  to  that  of  both  the  constituent  gases  taken 
together.     Thus,  if  50  cubic  inches  of  chlorine,  and   as   many 
of  hydrogen  be   exploded   by  electricity,  100   cubic   inches   of 
muriatic  acid  will  be  obtained  ;  and  as  the  weight  of  chlorine  is 
to  that  of  hydrogen  as  36  to  1,  their  combining  or  proportional 
numbers  must  be  in  the  same  ratio,  and  the  combining  number 
of  muriatic  acid  will  consequently  be  37. 

224.  Muriatic  acid  gas  is  colourless,  and  has  an  intensely  acid 
taste,  and  a  peculiar  pungent  smell.    It  cannot  be  respired,  and  it 
is  incombustible,  extinguishing  burning  bodies  plunged  into  it. 
Like  other  acids  it  reddens  vegetable  blues,  as  litmus  paper ;  but 
turmeric  paper  exposed  to  it  acquires  a  brown  tint,  not  unlike  that 
produced  by  an  alkali.     The  attraction  of  this  gas  for  water  is  very 
great,  so  that  it  immediately  forms  fumes  like  white  clouds,  when 
suffered  to  escape  into  the  air,  by  combining  with  the  water  con- 
tained in  it.     Water  at  the  temperature  of  40°,  absorbs  480  times 
its  own  bulk  of  muriatic  acid  gas,  being  at  the  same  time  increased 
in  quantity.    The  solution  forms  common  muriatic  acid,  which, 
when  pure,  is  colourless,  and  possesses  all  the  general  properties 
of  the  gas.     Its  specific  gravity  varies  according  to  the  quantity 
of  the  gas  with  which  the  water  is  combined ;  but  it  is  usually 
about  1.16  or  1.17. 

Who  first  ascertained  the  true  nature  of  muriatic  acid? 

By  whom  was  chlorine  first  obtained  from  this  acid  ? 

Jfow  may  it  be  directly  composed  from  chlorine  and  hydrogen  ? 

What  are  the  sensible  properties  of  muriatic  acid  gas? 

What  effect  has  it  upon  combustion  ? 

What  portion  of  it  may  be  absorbed  by  water  ? 


HYDRIODIC  ACID.  03 

225.  Muriatic  acid  is  commonly  procured  from  the  decompo- 
sition of  common  salt,  by  means  of  sulphuric  acid  diluted.     In 
this  case  a  double  decomposition  takes  place.     The  salt,  which 
is  a  compound  of  chlorine,  with  the  metal  sodium,  (the  basis  of 
soda,)  being  introduced  into  a  tubulated  retort,  on  adding  to  it  sul- 
phuric acid,  and  applying  heat,  the  water  mixed  with  the  acid  be- 
comes decomposed,  and  its  oxygen  uniting  with  the  sodium  forms 
soda,  which  combines  with  the  sulphuric  acid,  while  the  hydrogen 
of  the  water  unites  with  the  chlorine  thus  set  free,  to  form  mu- 
riatic or  hydrochloric  acid.     If  the  operation  be  conducted  over 
mercury,  the  gas  will  be  obtained  in  great  purity,  though  not 
free  from  water.    A  process  very  similar  to  this  is  usually  adopted 
for  procuring  liquid  muriatic  acid ;  the  gaseous  acid,  as  it  is  pro- 
duced, being  condensed  in  a  series  of  bottles,  each  containing  a 
small  quantity  of  water,  and  provided  with  safety  tubes. 

226.  Hydrogen  and  iodine,  placed  in  contact,  combine  slowly  at 
a  moderate  temperature,  but  the  union  more  readily  takes  place 
when  iodine  is  heated  in  hydrogen  gas ;  an  acid  gas  being  formed, 
which  is  rapidly  absorbed  by  water,  and  which  is  decomposed  by 
mercury,  and  therefore  cannot  be  preserved  long  over  that  fluid. 
The  gaseous  product  is  called  hydriodic  acid.     There  are  various 
modes  of  preparing  it,  one  of  the  most  convenient  of  which  is  by 
exposing  eight  parts  of  iodine  and  one  of  phosphorus,  moistened 
with  water,  in  a  small  retort,  to  a  gentle  heat,  when  the  gas  will 
be  evolved,  and  must  be  received  over  mercury,  but  transferred  as 
quickly  as  possible  into  an  exhausted  vessel,  or  it  may  be  allowed 
to  pass  over  into  a  bottle  filled  with  atmospheric  air,  in  the  manner 
directed  for   procuring  chlorine   gas;*  both   these   gases,  from 
their  specific  gravity,  being  capable   of  expelling  common  air 
in  a  great  measure  from  an  open  vessel  when  poured  into  it. 

227.  Hydriodic  acid  is  a  colourless  elastic  fluid,  having  a  sour 
taste,  reddening  vegetable  blues,  and  exhaling  an  odour  like  that 
of  muriatic  acid,  white  fumes  escaping  when  it  is  exposed  to  the 
atmosphere.      Its  specific  gravity  is  4.34,  that  of  atmospheric  air 
being  1 ;  and  100  cubic  inches  weighing  133.4  grains.   A  saturat- 
ed solution  of  hydriodic  gas  may  be  obtained  by  careful  evapora- 
tion of  water  impregnated  with  it,  by  passing  sulphuretted  hydro- 
gen through  a  mixture  of  iodine  and  water.     The  liquid  at-id  has 
a  specific  gravity  of  1.7.     It  dissolves  iodine,  acquiring  a  deep 
brown  colour,  and  it  is  decomposed  by  the  nitric  and  sulphuric 
acids.     The  acid  in  its  gaseous  state  is  decomposed  by  chlorine, 

What  process  is  commonly  employed  for  obtainining  muriatic  acid  ? 
What  succession  of  reactions  is  supposed  to  take  place  when  this  pro- 
cess is  employed  ? 

By  what  method  is  hydriodic  acid  most  conveniently  prepared  ? 
What  are  the  sensible  properties  of  this  gas  ? 

In  what  manner  may  hydriodic  acid  be  obtained  in  a  liquid  state  ? 
What  is  its  specific  gravity  ? 

*  See  above  No.  179. 


94 


CHEMISTRY. 


muriatic  acid  being  formed,  and  the  iodine  set  free,  forming  violet- 
coloured  fumes,  when  the  chlorine  is  mixed  with  atmospheric  air. 
From  the  action  of  mercury,  and  some  other  metals,  on  hydriodic 
acid  gas,  causing  the  evolution  of  half  its  volume  of  hydrogen,  it 
may  be  inferred  that  this  acid  is  composed  of  1  equivalent  of  each 
of  its  constituents,  and  therefore  its  combining  number  must  be 
124  -f  1  =  125. 

228.  Hydrogen  and  bromine  do  not  enter  into  combination,  when 
the  vapour  of  the  latter  is  mingled  with  the  former  and  exposed 
to  the  light  of  the  sun  ;  but  the  mixture  may  be  inflamed  by  in- 
troducing into  it  a  lighted  match,  or  red-hot  iron,  when  union  takes 
place,  but  without  explosion.     The  product  is  a  colourless  gas, 
which,  from  its  properties,  has  been  styled  hydrobromic  add.     It 
may  also  be  procured  from  the  decomposition  of  water,  by  means 
of  bromine  and  phosphorus,  in  a  mode  analogous  to  that  in  which 
hydriodic  acid  is  obtained. 

229.  The  hydrobromic  acid  gas  is  rapidly  absorbed  by  water, 
but  may  be  preserved  over  mercury.     Its  aqueous  solution  is  at 
first  colourless,  but  it  readily  dissolves  bromine,  and  receives  from 
it  a  yellow  tint.      It  is  decomposed  by  chlorine,  and  likewise  by 
nitric  acid,  but  not  so  easily  by  the  sulphuric  acid.      In  the  mode 
of  its  composition  it  resembles  the  hydriodic  acid,  and  may  be 
supposed  to  consist  of  1  atom  of  bromine  and  1  of  hydrogen,  so 
that  its  combining  number  will  be  75  -f-  1  =76. 

230.  Hydrogen  combines  with  fluorine  to  form  the  compound 
called  hydrofluoric  acid,  the  properties  and  method  of  procuring 
which  have  been  already  described.*  Fluorine  having  never  been 
obtained  in  a  separate  state,  its  equivalent  or  combining  number  can- 
not readily  be  ascertained.  It  has  been  variously  estimated,  from  16 
to  19  ;  and  since  hydrofluoric  acid  may  be  regarded  as  bearing  an 
analogy  of  constitution  to  the  other  hydrogen  acids,  it  must  be  con- 
sidered as  composed  of  1  atom  of  fluorine  and  1  of  hydrogen,  and  if 
19  be  taken  as  the  atomic  weight  of  the  former,  that  of  the  latter 
must  consequently  be  19  -f-  1  =  20. 

231.  Hydrogen  forms  compounds  with  a  few  only  of  the  electro- 
positive bodies,  as    nitrogen,  sulphur,  phosphorus,  arsenic,  and 
tellurium  ;  and  the  most  important  of  these  combinations  will  be 
subsequently  described.     In  some  respects  hydrogen,  in  a  varietv 
of  chemical  operations,  appears  to  act  as  a  sort  of  antagonist  power 
to  oxygen,  the  one  exhibiting  the  highest  degree  of  electro-negative 

What  are  the  results  of  its  decomposition  by  chlorine  ? 

What  number  of  volumes  of  each  constituent  enter  into  hydriodic  acid  ? 

What  is  its  atomic  weight  ? 

What  combination  is  hydrogen  capable  of  forming  withTsromine  ? 

What  with  fluorine  ? 

What  is  supposed  to  be  the  atomic  constitution  of  this  latter  compound  ? 

With  which  of  the  electro-positive  bodies  may  hydrogen  combine  ? 

What  electrical  relation  does  this  gas  appear  to  sustain  to  oxygen  ? 

*  See  above  No.  201. 


NITROGEN.  95 

energy,  and  the  other  perhaps  the  utmost  electro-positive 
energy.  Next  to  oxygen  it  is  apparently  the  most  widely  extended 
and  abundant  of  all  known  bodies.  Like  oxygen,  also,  it  forms, 
in  combination  with  other  elements,  three  sorts  of  compounds : 
thus,  with  chlorine,  iodine,  &c.,  it  constitutes  acids ;  with  nitro- 
gen, ammonia,  a  salifiable  basis  ;  and  with  oxygen  itself  it  forms 
water,  with  arsenic,  arseniuretted  hydrogen,  neither  of  which 
bodies  have  acid  or  alkaline  properties.* 

Nitrogen. 

232.  As  this  gas  is  contained  in  a  large  pro- 
portion  in  atmospheric  air,  it  may  be  procured  by 
burning  phosphorus,  in  air  inclosed  over  water,  in 
a  tall  glass  jar.  The  phosphorus  may  be  placed 
in  a  small  basin  of  wedgwood  ware,  as  in  the 
annexed  figure ;  and  after  having  been  inflamed 
with  a  red-hot  iron,  it  is  to  be  covered  with  the 
inverted  jar  or  bell-glass,  A.  The  jar  should  have 
an  open  neck  at  top,  filled  with  a  stopper,  which 
must  not  be  inserted  at  first,  part  of  the  air,  ex- 
panded by  heat,  being  allowed  to  make  its  escape  :  the  stopper  is 
then  to  be  replaced,  and  the  combustion  suffered  to  continue,  till 
the  phosphorus  becomes  extinguished,  in  consequence  of  all  the 
oxygen  having  been  consumed.  The  remaining  gas,  after  the  jar 
has  cooled,  must  be  well  washed  with  lime-water,  and  the  pro- 
duct will  be  pure  nitrogen. 

233.  This  gas  may  also  be  obtained  by  allowing  atmospheric 
air  to  stand  in  an  inverted  jar,  over  a  mixture  of  equal  parts  of  iron 
filings  and  sulphur,  made  into  a  paste  with  water ;  which  mixture 
would  absorb  the  oxygen   of  the  air,  and  leave  the  nitrogen  be- 
hind.     Another  method  of    procuring    nitrogen   is   by  passing 
chlorine  gas  through  a  strong  solution  of  ammonia  in  water.     In 
this  case  the  ammonia,  which  is  a  compound  of  hydrogen  and 
nitrogen,  becomes  decomposed  by  the  chlorine,  which  unites  with 
its  hydrogen  to  form  muriatic  acid,  and  the  nitrogen  is  given  out. 
If,  however,  a  large  proportion  of  chlorine  be  used,  chloride  of 
nitrogen  will  be  formed. 

234.  Nitrogen,  however  it  may  be  obtained,  is  a  permanently 
elastic  fluid,  it  having  hitherto  resisted  all  attempts  to  reduce  it  to 
the  liquid  state  by  compression  and  low  temperature.      It  is  a 
colourless  gas,  destitute  of  taste  and  smell,  unfit  for  respiration, 
and  is  neither  inflammable  nor  capable  of  supporting  combustion, 

In  what  manner  may  nitrogen  be  procured  from  atmospheric  air  ? 

Describe  the  apparatus  adapted  to  this  purpose. 

In  what  manner  are  sulphur  and  iron  employed  for  fhe  same  purpose  ? 

How  chlorine  and  ammonia? 

What  is  the  explanation  of  the  latter  process  ? 


*  Journal  of  Science,  ed.  at  R.  I.,  vol.  i.  p.  286. 


96  CHEMISTRY. 

burning- bodies  introduced  into  it  becoming  instantly  extinguished. 
It  has  no  action  on  vegetable  colours,  nor  upon  lime-water,  and  is 
absorbed  by  water  only  in  a  very  minute  proportion.  Its  weight 
is  fourteen  times  that  of  hydrogen,  and  it  is  therefore  somewhat 
lighter  than  atmospheric  air. 

235.  Nitrogen  enters  into  combination  with  oxygen  in  various 
proportions,  forming  several  important  chemical  compounds.  It 
is  likewise,  as  already  stated,  one  of  the  constituents  of  atmos- 
pheric air,  which  consists  of  this  gas,  mixed  with  oxygen,  and 
small  quantities  of  aqueous  vapour  and  carbonic  acid  gas  ;  but  these 
latter  bodies  appear  to  exist,  not  only  in  comparatively  minute, 
but  also  in  variable  quantities.  The  physical  properties  of  atmos- 
pheric air  have  been  already  described  and  elucidated  in  the 
Treatise  on  Pneumatics  ;  the  notice  of  it  here  will  therefore  be 
confined  to  its  chemical  properties  and  modes  of  action. 

236.  It  is  now  generally  admitted  by  chemists,  that  though  the 
essential  constituents  of  atmospheric  air,  oxygen  and  nitrogen, 
are  always  found  in  the  same  proportions,  yet  this  compound  gas, 
in  which  we  live  and  breathe,  is  a  mere  mixture  of  its  component 
parts.  Considered  in  this  point  of  view,  common  air  presents  a 
wonderful  uniformity  in  various  situations.  For  air,  collected  by 
means  of  a  balloon,  at  the  distance  of  more  than  21,000  feet  above 
the  surface  of  the  earth,  or  at  the  level  of  the  sea,  procured  from 
the  interior  of  crowded  towns  or  cities,  or  from  the  tops  of  high 
mountains,  and  from  the  equatorial,  or  from  the  polar  regions  of 
the  earth,  is  found  to  contain  about  one  part,  by  measure,  of 
oxygen,  and  four  of  nitrogen. 

237.  The  general  constitution  of  the  atmosphere  may  be  thus 
more  exactly  stated  : 

By  Measure.  By  Weight. 

Nitrogen  .  77.5  .  .  .  75.55 
Oxygen  .21.  ...  23.32 
Aqueous  vapour  1.42  .  .  .  1.03 
Carbonic  acid  0.08  .  .  .  0.10 

100.  100." 

The  quantity  of  aqueous  vapour  must,  however,  always  depend 
on  the  temperature  of  the  air  and  its  relation  to  the  dew-point.* 

238.  Since  nitrogen  gas  is  characterized  chiefly  by  negative 
properties,  and  is  especially  unfit  for  respiration,  the  purity  of  the 
atmosphere  is  always  estimated  by  the  quantity  of  oxygen  gas 
which  it  contains;  and  hence  the  employment  of  instruments 

What  are  the  leading  properties  of  nitrogen  ? 

In  what  state  is  it  supposed  to  exist  in  almospheric  air? 

What  has  been  found  to  be  the  constitution  of  air  brought  from  great 
heights  ? 

What  proportion  by  measure  and  by  weight  are  the  two  chief  ingredi- 
ents of  atmospheric  air  always  found  to  maintain  ? 

*  See  Treatise  on  Meteorology. 


PROTOXIDE  OF  .NITROGEN.  97 

called  eudiometers,  consisting-  in  general  of  tubes,  adapted  to  ap- 
paratus for  absorbing  or  consuming  the  oxygen  of  a  given  quantity 
of  air,  and  for  measuring  the  residuum. 

239.  Among  the  chemical  compounds  of  nitrogen  and  oxygen, 
the  first  is  the  protoxide  of  nitrogen,  containing  a  larger  proportion 
of  oxygen  than  is  found  in  common  air,  but  less  than  in  any  other 
of  the  chemical  compounds.     This  oxide,  which  is  a  gaseous 
body,  was  discovered  by  Dr.  Priestley  in  1776,  and  by  him  termed 
dephlogisticated  nitrous  air ;  by  others  it  has  been  styled  gaseous 
oxide  of  azote ;  and  as  elsewhere  mentioned,  from  its  effects  when 
respired,  intoxicating  gas.     It  may  be  obtained  by  exposing  the 
next  compound,  nitric  oxide,  over  a  mixture  of  sulphur  and  iron 
filings  ;  by  which  the  oxygen  will  be  partially  absorbed,  and  the 

.protoxide  formed.  It  may,  however,  be  obtained  more  readily, 
and  in  a  state  of  greater  purity,  by  heating  in  a  glass  retort  over  a 
lamp  the  salt  called  nitrate  of  ammonia,  which  becomes  decom- 
posed at  the  temperature  of  about  420°,  into  hydrogen  arid  pro- 
toxide of  nitrogen. 

240.  The  gas  thus  obtained  is  destitute  of  colour,  and  has  a 
sweet  taste,  and  a  peculiar  agreeable  srnell.    It  is  easily  absorbed 
by  cold  water,  which  takes  up  about  its  own  bulk  of  this  gas,  and 
gives  it  out  when  heated.  It  does  not  change  the  colour  of  vegetable 
blues.     It  is  a  supporter  of  combustion,  and   a  taper  introduced 
into  it,  which  has  been  lighted  and  just  extinguished,  will  be  re- 
kindled, and  burn  with  an  enlarged  flame,  surrounded  by  a  purplish 
halo.     Iron  wire  or  charcoal,  previously  made  red-hot,  will   burn 
in  it  almost  as  brilliantly  as  in  oxygen  gas,  but  for  a  shorter  time. 
Phosphorus  and  sulphur,  when  introduced  into  it  while  in  a  state 
of  active  inflammation,  burn  with  great  violence  ;  but  if  immersed 
in  this  gas  while  they  are  burning  but  faintly,  the  flame  becomes 
extinguished. 

241.  When  mixed  with  hydrogen,  the  protoxide  of  nitrogen  may 
be  made  to  detonate  by  means  of  flame,  or  of  an  electric  spark. 
Two  cubic  inches  of  the  protoxide  require  two  cubic  inches  of 
hydrogen  for  its  decomposition  ;  water  in  this  case  being  produced, 
and  two  cubic  inches  of  nitrogen  remaining.     Now,  since  two 
cubic  inches  of  hydrogen  require  one  cubic  inch  of  oxysren  to  form 
water,  the  protoxide  of  nitrogen  must  be  composed  of  two  cubic 
inches,  or  volumes  of  nitrogen  and  one  of  oxygen,  condensed  into 
the  space  of  two  volumes. 

242.  The  singular  effect  of  this  gas  when  breathed  has  been 
already  mentioned.     Though  the  temporary  use  of  it  is  seldom  at- 
tended with  inconvenience,  yet,  from  the  great  excitement  it  pro- 
duces, it  cannot  be  long  breathed  without  danger.      Experiments 

By  whom  was  protoxide  of  nitrogen  first  obtained  ? 
How  is  it  obtained  from  nitrate  of  ammonia? 
What  are  its  sensible  and  chemical  properties  ? 
How  does  it  react  when  heated  with  hydrogen  ? 

What  reasoning  on  this  experimnt  leads  us  to  the  true  constitution  of 
protoxide  of  nitrogen  ? 


98  CHEMISTRY. 

relative  to  its  effects  may  be  made  by  filling  a  clean  bladder  with 
some  of  the  gas,  the  purity  of  which  has  been  previously  ascer- 
tained, and  it  may  then  be  inhaled  through  a  pipe,  with  a  stop- 
cock adapted  to  it.  Different  persons  are  variously  affected  by 
it;  with  some  it  appears  to  be  nearly  inactive,  but  most  persons 
on  using  it  feel  their  spirits  greatly  exhilirated,  as  by  the  moderate 
use  of  wine  ;  and  upon  the  whole,  it  may  be  regarded  as  occasion- 
ing the  incipient  and  most  agreeable  effects  of  intoxication. 
/  243.  The  nitric  oxide  or  deutoxide  of  nitrogen,  though  not  first 
discovered,  was  first  carefully  examined  by  Dr.  Priestley,  who 
gave  it  the  name  of  nitrous  gas.  It  may  be  obtained  by  decom- 
posing nitric  acid  by  means  of  metals,  as  by  pouring  the  acid  on 
copper  filings,  in  a  retort,  and  collecting  the  fumes  which  will  be 
produced  over  water.  The  first  portions  that  pass  over  are  con- 
taminated with  nitrogen  and  nitrous  acid  gas,  and  should  there- 
fore be  rejected.  Nitric  oxide  is  a  colourless,  gaseous  fluid, 
sparingly  soluble  in  water,  and  not  affecting  the  colour  of  vegeta- 
ble blues.  It  is  quite  unfit  for  respiration.  Most  flaming  bodies, 
as  burning  sulphur,  are  extinguished  when  immersed  in  it;  but 
charcoal  and  phosphorus  readily  burn,  if  introduced  into  it  in  a 
state  of  intense  ignition.  It  does  not  explode  with  hydrogen  in 
any  proportion,  but  produces  a  green  flame,  if  burnt  with  it,  in 
common  air.  When  nitric  oxide  is  mixed  with  oxygen  gas,  deep 
red  fumes  are  formed,  which  are  readily  absorbed  by  water;  and 
the  same  phenomenon  takes  place  when  this  gas  is  mixed  with 
the  atmosphere,  or  with  any  air  containing  oxygen.  Supposing 
the  atomic  weight  of  nitrogen  to  be  14,  this  oxide  consisting  of  I 
atom  of  nitrogen  and  2  of  oxygen,  its  combining  weight  must  be 
14+16  =  30. 

244.  Hyponitrous  acid  is  a  compound  of  nitrogen  and  oxygen,  in- 
termediate as  to  nitric  oxide  and  nitrous  acid,  which  was  discovered 
by  Gay  Lussac.  It  may  be  produced  by  mixing  nitric  oxide  and  oxy- 
gen over  mercury,  with  a  little  concentrated  solution  of  potash  float- 
ing above  it.     The  proper  proportions  are  four  volumes  of  nitric 
oxide  and  one  of  oxygen,  which  combine  together  and  unite  with 
the  potash  ;  from  which  the  hyponitrous  acid  cannot  be  disengaged 
without  decomposition. 

245.  Nitrous  acid  is  the  next  compound,  which  may  likewise 
be  formed  by  adding  oxygen  to  the  nitric  oxide ;  this,  however, 
must  be  done  in  an  exhausted  glass  vessel,  for  the  nitrous  acid  is 

What  effects  does  it  produce  on  the  system  when  inhaled  ? 
What  name  did  Priestley  apply  to  the  deutoxide  of  nitrogen  ? 
In  what  manner  is  that  gas  obtained  ? 
What  are  its  properties  ? 

What  substances  may  be  maintained  in  a  state  of  ignition  within  it? 
How  does  it  act  upon  oxygen  ? 
What  are  its  composition  and  atomic  weight  ? 

In  what  compound  does  the  next  degree  of  oxygenation  above  that  of 
deutoxide  of  nitrogen  exist? 

By  whom  was  hyponitrous  acid  discovered? 
State  its  composition  and  properties. 


CHLORIDE  OF  NITROGEN.  99 

absorbed  both  by  water  and  by  mercury.  When  two  volumes 
of  nitrous  oxide  and  one  volume  of  oxygen,  are  thus  mixed,  heat 
is  evolved,  and  the  gases  become  condensed  to  one-third  of  their 
original  bulk,  forming  nitrous  acid.  This  gas,  which  becomes 
reduced  to  the  liquid  state  at  zero  of  Fahrenheit,  is  readily  absorbed 
by  water,  forming  an  acid  liquor.  Nitrous  acid  gas  supports  the 
combustion  of  charcoal  and  phosphorus,  but  extinguishes  burning 
sulphur. 

246.  Nitric  add  is  a  compound  in  which  oxygen  exists  in  the 
largest  proportion.     It  is  said  to  have  been  produced  in  a  minute 
quantity  by  passing  electric  sparks,  for  a  long  time,  through  a 
mixture  of  nitrogen  with  oxygen  ;  but  it  may  be  more  readily  ob- 
tained by  passing  nitric  oxide  very  slowly  into  oxygen  gas  over 
water.     However,  the  usual  mode  of  procuring  it  is  by  the  decom- 
position of  nitre  (nitrate  of  potash)  with  sulphuric  acid  ;  the  latter 
entering  into  combination  with  the  potash,  and  the  nitric  acid  may 
be  distilled  over  :  thus  procured,  it  contains  at  least  one-fourth  its 
weight  of  water,  and  is  therefore  called  hydrated  nitric  acid,  and 
popularly  aqua  fortis.     In  this  state  it  is  a  transparent  liquid, 
colourless  when  pure,  having  an  intensely  sour  taste,  and  acting 
powerfully  on  animal  substances,  tinging  the  skin  yellow  when 
but  lightly  applied  to  it.      It  acts  with  great  energy  on  most  sub- 
stances which  have  an  affinity  for  oxygen,  and  which  thus  decom- 
pose it. 

247.  When  brought  in  contact  with  hydrogen,  at  an  elevated 
temperature,  a  violent  explosion   takes   place ;    the   experiment 
therefore  cannot  be  made  without  danger.  If  it  be  poured  on  warm, 
dry,  pulverized   charcoal,  inflammation  ensues ;     and  abundant 
fumes  of  nitric  oxide  are  given  out.      Inflammation  may  also  be 
produced  by  pouring  nitric  acid  on  spirit  of  turpentine  ;  but  this 
experiment  requires  caution,  and  the  best  method  of  performing 
it  is  by  affixing  the  phial  containing  the  acid  to  the  end  of  a  long 
rod,  as  some  degree  of  explosion  takes  place.    Other  essential  oils 
may  also  be  inflamed  by  this  acid  ;  and  with  oil  of  amber,  it  forms 
a  resinous  compound,  which   has  been  called   artificial   musk, 
having  an  odour  somewhat  resembling  that  of  musk. 

248.  Chloride  of  nitrogen. — Nitrogen  combines  with  chlorine, 
though  their  mutual  affinity  is  inconsiderable ;  and  therefore  the 
compound  is  most  readily  obtained   by  the  indirect  process  of 
passing  a  current  of  chlorine  gas  through  a  solution  of  any  salt 
containing  ammonia,  at  a  temperature  of  about  90°.  The  salt  best 
adapted  for  this  purpose  is  nitrate  of  ammonia,  or  that  which  is 
obtained  by  the  union  of  nitric  acid  with  ammonia.  The  compound 

How  many  volumes  of  nitrogen  and  oxygen  respectively  form  nitrous 
acid? 

In  what  manner  is  nitric  acid  best  procured  ? 

What  name  is  commonly  applied  to  this  acid  ? 

On  what  class  of  bodies  does  it  act  with  peculiar  energy  ? 

How  does  it  react  with  charcoal  and  essential  oils? 

In  what  manner  is  chloride  of  nitrogen  best  procured  ? 


100  CHEMISTRY. 

called  chloride  of  nitrogen  then  appears,  first  in  the  form  of  an 
oily  film  on  the  surface  of  the  saline  solution,  which  collects  into 
yellowish  drops,  and  sinks  to  the  bottom  of  the  vessel.  This  is 
ono  of  the  most  powerful  explosive  compounds  with  which  we  are 
acquainted  ;  and  it  is,  therefore,  too  dangerous  and  unmanageable 
to  be  applied  to  any  useful  purpose,  and  experiments  made  on  it 
require  the  utmost  care  and  caution. 

249.  M.  Dulong,  who  discovered  this  substance  in   1812,  lost 
an  eye  and  the  use  of  a  finger  by  its  explosion  ;  and  Sir  FI.  Davy, 
who  afterwards  made  experiments  on  it,  was  wounded  in  the  face 
It  explodes  with  extreme  violence  at  the  temperature  of  about 
200°  ;  but  the  mere  contact  of  sulphur,  phosphorus,  oil,  and  some 
other  inflammable  bodies,  causes  its  detonation  at  common  tem- 
peratures.    The  composition  of  chloride  of  nitrogen  has  been  dif- 
ferently estimated  by  different  writers.     It  consists,  according  to 
some,  of  14  Nitr.  -f- 108  Ch. ;    while  others   state  it  to  be  14 
Nitr.  -f-  144  Ch. 

250.  With  iodine,  nitrogen  forms'  a  compound  called  iodide  of 
nitrogen.     It  may  be  obtained  by  pouring  a  solution  of  ammonia 
upon  a  very  small  quantity  of  iodine.     It  is  an   insoluble  black 
powder,  highly  explosive,  as  the  slightest  touch  will   sometimes 
cause  detonation.      When  left  exposed  to  the  air  it   gradually 
evaporates  ;  or  if  moist,  becomes  decomposed  into  nitrogen,  and 
iodic  and  hydriodic  acids ;  and  it  is  likewise  decomposed  by  hot 
water,  and  by  alkaline  solutions. 

251.  Ammonia. — Nitrogen  and    hydrogen  may  be  mixed  to- 
gether  in   any  proportions   without  combining ;    but   indirectly 
they  may   be   united,  forming    the    gaseous    compound    called 
volatile  alkali  or  ammonia.     This  appears,  under  certain  circum- 
stances, to  be  formed  naturally,  being  found  in  Egypt  and  some 
other  countries  in  combination  with  muriatic  acid,  constituting 
the  saline  substance  known  in  the  shops  by  the  name  of  sal-am- 
moniac.    From  this  salt  ammonia  is  most  readily  procured.     One 
part  of  muriate  of  ammonia,  (sal-ammoniac,)  and  two  parts  of  dried 
quicklime,  both  powdered,  must  be  introduced  into  a  small  glass 
retort ;   and  upon  the  application  of  a  gentle  heat,  a  pungent  gas 
will  be  evolved,  which  is  ammonia.     It  may  be  collected  over 
mercury,  or  .if  collected  over  water,  it  may  be  rapidly  absorbed  by 
that  fluid,  constituting  the  liquor  of  ammonia. 

252.  This  alkali  is  at  common  temperatures  a  permanently 
elastic  fluid  ;  but  it  has  been  reduced  to  the  liquid  state,  by  means 
of  cold  and  pressure,  by  Mr.  Faraday.  In  this  form  it  is  a  colour- 
less, transparent  liquid,  of  the  specific  gravity  of  0.76  ;  and  its  re- 

What  is  related  of  the  peculiar  action  of  this  substance  ? 

What  estimates  have  been  formed  of  its  composition  ? 

What  name  is  given  to  the  compound  of  iodine  and  nitrogen  ? 

What  are  its  properties  ?     How  is  ammonia  produced  ? 

In  what  state  does  it  exist  at  common  temperatures  ? 

By  what  means  can  it  be  reduced  to  a  liquid  ? 

What  is  its  specific  gravity  in  this  stale  ? 


CARBON.  101 

Tractive  power  exceeds  that  of  water.  Ammoniacal  gas  is  much 
lighter  than  atmospheric  air;  its  specific  gravity,  compared  with 
that  of  hydrogen,  being  as  8.5  to  1.  It  has  a  very  acrid  odour, 
which  is  not  disagreeable  when  considerably  diluted  with  com- 
mon air.  It  cannot  be  respired  alone,  as  animals  instantly  die 
when  immersed  in  it ;  and  burning  bodies  are  extinguished  by  it. 
The  gas  itself  is  somewhat  inflammable,  for  a  small  jet  of  it 
thrown  into  a  jar  of  oxygen  will  burn,  the  products  being  water 
and  hydrogen.  It  turns  vegetable  blues  to  green,  and  renders  yel- 
lows brown,  like  other  alkalies  ;  but  the  effect  is  not  permanent, 
for  as  the  gas  exhales,  the  original  colours  return. 

253.  Water,  at  the  temperature  of   50°  takes  up  670  times  its 
bulk  of  ammoniacal  gas;    becoming  increased  in  quantity,  and 
lowered  in  specific  gravity.      In  this  staj£  the  liquor  of  ammonia 
is  commonly  used,  both  for  chemical  and  medical  purposes.   This 
liquid  absorbs  carbonic  acid  when  exposed  to  the  air,  and  should 
therefore  be  preserved  in  well-stopped  glass  bottles.  At  the  heat  of 
about  140°,  ammonia  is  rapidly  evolved  from  it.      When  concen- 
trated, it  congeals  at  40°,  assuming  a  gelatinous  appearance,  and 
losing  its  odour. 

254.  When  ice  is  introduced  into  a  jar  of  ammoniacal  gas,  it 
melts  quickly,  absorbing  the  gas,  and  forming  liquor  of  ammonia. 
This  gas  may  be  decomposed  into  its  constituent  parts,  by  passing 
it  through  a  red-hot  tube ;  and  the  decomposition  may  be  hastened 
by  filling  the  tube  with  coils  of  iron  wire,  and  thus  presenting  to 
the  gas  a  larger  heated  surface.     The  products  may  be  received 
in  a  jar  inverted  over  water.     Dr.  Henry  ascertained  that  a  mix- 
ture of  ammonia  and  oxygen  gas  might  be  inflamed  by  the  elec- 
tric spark. 

255.  The  alkaline  gas  also,  alone,  may  be  decomposed,  by 
passing  through  it  a  succession  of  electrical  sparks :  by  this  pro- 
cess its  volume  becomes  increased,  and  a  cubic  inch  of  it  may  be 
augmented  to  double  that  bulk,  by  passing  two  or  three  hundred 
charges  of  electricity  through  it.     Ammonia  is  formed  during  the 
decomposition  of  many  animal  substances:  the  production  of  this 
gas  also  takes  place  in  consequence  of  the  violent  action  of  nitric 
acid  upon  phosphorus  and  some  of  the  metals,  and  it  is  formed  by 
exposing  to  an  atmosphere  of  nitrogen,  moistened  iron  filings ; 
and  in  certain  other  cases,  in  which  the  gases  composing  it  are 
given  off  simultaneously,  under  peculiar  circumstances. 

Carbon. 

256.  The  physical  properties  of  this  substance  in  its  usual  state 
of  aggregation,  as  procured  from  the  distillation  of  animal  and 

What  effect  has  it  on  respiration  ? 
In  what  proportions  is  it  absorbed  by  water? 

What  effect  has  ammoniacal  gas  upon  ice  ?    What  results  from  this  action? 
How  may  ammoniacal  gas  be  decomposed  ? 
What  action  has  electricity  upon  it  ? 
By  what  natural  processes  may  ammonia  be  obtained  ? 
i  2 


102  CHEMISTRY. 

vegetable  substances,  are  too  well  known  to  require  a  particular 
description.  This  body  may  be  obtained  in  a  state  of  charcoal, 
for  experimental  purposes,  by  covering  pieces  of  wood  with  sand 
in  a  large  crucible,  and  exposing  them  for  about  an  hour  to  a 
very  intense  heat.  The  charcoal  used  in  various  arts  and  manu- 
factures is  commonly  prepared  on  an  extensive  scale,  by  the  im- 
perfect combustion  of  wood,  built  up  in  large  piles,  and  covered 
with  turf;  or  else  by  the  distillation  of  wood  in  cast  iron  cylin- 
ders. Lampblack  is  also  chiefly  composed  of  charcoal,  consisting 
of  soot,  collected  from  the  combustion  of  the  refuse  resin,  obtained 
in  making  turpentine.  Ivory-black  is  another  carbonaceous  sub- 
stance which  results  from  the  burning  of  bones  in  close  vessels. 
Coke  is  chiefly  composed  of  charcoal,  arising  from  the  distillation 
of  coal,  as  in  the  coal-gas  manufactories;  but  it  is  often  contami- 
nated with  sulphur  and  earthy  matter. 

257.  Carbon,  as  already  stated,  appears  to  exist  in  the  purest 
form  in  the  diamond.    That  this  splendid  gem  v/as  an  inflammable 
substance,  Sir  Isaac  Newton  sagaciously  conjectured,  from  ob- 
serving that  it  was  possessed  of  high  refractive  power ;  this  idea 
derived  confirmation  from  the  experiments  of  the  Florentine  aca- 
demicians in  1694;  and  it  has  been  verified  more  recently  by  the 
researches  of  Guyton  Morveau,  Smithson  Tennant,  Sir  H.  Davy, 
and  other  philosophers.     The  diamond,  in  its  natural  state,  is 
composed  of  octaedral  crystals.     It  is  brittle,  but  appears  to  be 
harder  than  any  other  substance ;  and  hence  the  powder  of  dia- 
mond is  used  for  cutting  and  polishing  the  hardest  gems,  and  the 
diamond  itself,  for  the  purposes  of  ornamental  jewellery. 

258.  Carbon,  as  commonly  procured  by  distilling  wood,  is  a 
good  conductor  of  electricity,  though  a  bad  conductor  of  heat.    It 
remains  unchanged  by  air  or  water  at  common  temperatures ;  but 
when  highly  heated,  readily  burns  in  oxygen  gas  or  common  air. 
It  has  the  property  of  destroying  the  smell  and  taste  of  many 
animal  and  vegetable  substances ;  and  it  powerfully  resists  putre- 
faction, so  that  tainted  meat,  if  covered  with  new-burnt  charcoal 
for  a  few  hours,  becomes  perfectly  sweet, 

259.  The  colours  of  vegetable  substances  are  also  greatly  affected 
by  charcoal ;  and  hence  it  is  sometimes  added  to  port  wine  for 
the  purpose  of  giving  it  a  tawny  hue.     Vinegar  boiled  with  it 
becomes  colourless;  and  it  is  largely  used  in  refining  sugar,  in 
procuring  transparent  crystals  of  citric  acid,  and  in  other  processes. 
Charcoal  obtained  by  the  distillation  of  animal  substances  is  found 
most  serviceable  for  these  purposes.     Freshly-prepared  charcoal 

What  is  the  process  for  procuring  charcoal? 
How  is  lampblack  obtained  ? 
What  is  the  nature  of  ivory  black? 
Whence  is  coke  procured  ? 

In  what  state  is  carbon  found  in  the  greatest  purity  ? 
From  what  observation  was  the  inflammability  of  the  diamond  conjec- 
tured ?     What  are  its  chief  physical  properties  ? 
What  are  the  chemical  uses  of  charcoal  ? 
What  kind  of  charcoal  is  employed  for  these  purposes  ? 


COMBUSTION  OF  THE  DIAMOND.  103 

largely  absorbs  various  gases,  a  property  which  appears  to  depend 
on  the  texture  of  the  charcoal ;  and  the  different  kinds  of  this 
substance  absorb,  in  various  proportions,  aqueous  vapours  con- 
tained in  the  air. 

260.  Carbon  unites  with  oxygen  to  form  three  or  more  com- 
pounds, an  oxide  and  various  acidsi     The  former  of  these,  car- 
bonic oxide,  is  a  gaseous  body,  discovered  by  Dr.  Priestley ;  and 
the   properties  of  which  were  afterwards  investigated  by  Mr. 
Cruikshank,  and  by  MM.  Clement  and  Desormes  in  France./  It 
may  be  produced  from  the  decomposition  of  the  compounds  con- 
taining carbonic  acid,  as  by  heating  in  an  iron  retort  a  mixture  of 
chalk  (carbonate  of  lime)  and  charcoal,  or  of  equal  weights  of 
chalk  and  filings  of  iron  or  zinc.'    The  gas  resulting  from  either  of 
these  operations  may  be  collected  in  a  jar  inverted  and  filled  with 
water;  and  it  must  be  purified  by  agitating  it  with  lirne-water,  to 
absorb  any  carbonic  acid  which  may  be  mixed  with  it.    Carbonic 
oxide  gas  is  destitute  of  colour  and  taste ;  but  it  has  a  disagreeable 
smell,  and  is  highly  injurious  to  animals^  producing  giddiness 
and  fainting,  if  respired  when  mixed  with  atmospheric  air.     It  is 
rather  lighter  than  common  air,  100  cubic  inches  weighing  29.65 
grains.     It  extinguishes  flame,  but  burns  with  a  faint  blue  light 
when  combined  with  atmospheric  air. 

261.  When  a  stream  of  this  gas  is  burnt  under  a  dry  bell-glass, 
In  common  air  or  oxygen  gas,  no  deposition  of  moisture  takes 
place,  as  in  the  combustion  of  hydrogen  and   its  compounds. 
If  carbonic  oxide,  with  an  equal  volume  of  hydrogen,  be  passed 
through  a  red-hot  porcelain  tube,  the  tube  will  become  lined  with 
carbon,  arising  from  the  decomposition  of  the  oxide,  and  water 
will  be  formed  ;  showing  that  at  a  high  temperature,  oxygen  has 
a  greater  affinity  for  hydrogen  than  for  carbon.     When  carbonic 
oxide,  mixed  with  half  its  volume  of  oxygen,  is  exposed  in  a  de- 
tonating tube  to  the  electric  spark,  an  explosion  will  take  place, 
and  a  quantity  of  carbonic  acid  will  be  formed,  equal  in  bulk  to 
the  carbonic  oxide.     Hence  it  appears  that  carbonic  oxide  con- 
tains just  half  as  much  oxygen  as  carbonic  acid.    . 

262.  Carbonic  acid,  or,  as  it  was  formerly  called, .fixed  air,  is  a 
compound  gas,  formed  both  by  art  and  nature,  in  a  variety  of  pro- 
cesses.    An  abundant  production  of  this  gas  takes  place  in  the 
combustion  of  animal  and  vegetable  substances  in  general ;  but 
the  most  interesting  example  of  the  formation  of  carbonic  acid 
occurs  when  the  diamond  is  intensely  heated  in  common  air  or 
oxygen  gas.     This  extremely  dense  and  apparently  permanent 

In  how  many  proportions  is  carbon  capable  of  uniting  with  oxygen  ? 
How  may  carbonic  oxide  be  procured  ? 
What  effects  does  it  produce  when  respired  ? 
What  are  its  chief  chemical  properties? 

What  effect  arises  from  heating  it  in  mixture  with  hydrogen  ? 
What  product  results  from  exploding  a  volume  of  carbonic  oxide  with 
half  a  volume  of  oxygen  ? 

What  name  was  formerly  applied  to  carbonic  acid  ? 


104 


CHEMISTRY. 


substance,  under  these  circumstances,  becomes  wholly  converted 
into  carbonic  acid  ;  a  result  which  plainly  demonstrates  it  to  con- 
sist of  carbon  alone.  The  combustion  of  the  diamond,  with'  a 
view  to  ascertain  with  accuracy  the  products  of  the  operation, 
appears  to  have  been  first  undertaken  by  (Lavoisier  in  1772.  In 
1797,  Mr.  Tennant  determined  from  experiment  that  equal  quan- 
tities of  carbonic  acid  were  obtained  when  equal  weights  of  dia- 
mond or  of  the  purest  charcoal  were  deflagrated  with  red-hot  nitre ; 
and  more  direct  experiments  were  subsequently  made,  by  causing 
the  diamond  to  undergo  combustion  in  oxygen  gas. 

263.  This  last  process  may  be  conveniently  executed  by  means 
of  the  apparatus  exhibited  in  the  annexed  diagram.     It  consists 


of  a  glass  globe,  containing  about  140  cubic  inches,  having  fitted 
to  its  neck  a  copper  cap,  with  a  large  apperture,  into  which  a  stop- 
cock is  screwed,  and  from  which  a  jet-pipe,  A,  rises  into  the  in- 
terior of  the  globe.  Just  above  this  jet,  two  wires,  CC,  terminate, 
at  a  short  distance  apart,  one  of  them  being  attached  to  the  side 
of  the  jet,  and  the  other  passing  through  an  insulating  glass  tube, 

By  whom  was  carbonic  acid  first  obtained  from  the  diamond  ? 
Describe  the  apparatus  in  which  the  combustion  of  the  diamond  may  be 
effected  ? 


CARBONIC  ACID.  105 

to  the  outside  of  the  apparatus,  forming  the  ring  D.  On  the  end 
of  the  jet  is  fixed  by  a  socket  a  small  capsule,  B,  made  of  platina 
foil,  and  pierced  with  holes  like  a  sieve.  It  is  placed  about  three- 
quarters  of  an  inch  from  the  extremity  of  the  jet,  and  the  arm 
that  supports  it  is  bent  so  that  the  stream  of  hydrogen,  used  to  set 
the  diamond  on  fire  shall  not  play  against  it.  The  lower  part  of 
the  stop-cock  screws  on  a  small  pillar,  fixed  to  a  stand  ;  and  at 
the  side  is  an  aperture,  from  which  passes  a  tube  with  another 
stop-cock,  by  which  a  bladder  filled  with  hydrogen  gas  may  be 
connected  with  the  apparatus. 

264.  When  a  diamond  is  to  be  submitted  to  combustion,  it  is 
to  be  placed  in  the  capsule  B,  and  the  globe  must  be  removed 
from  the  pillar  and  placed  on  an  air-pump,  and  when  exhausted, 
refilled  with  oxygen  gas.     It  is  then  to  be  carefully  screwed  on 
the  pillar  again,  and  the  bladder  of  hydrogen  gas  attached  to  the 
lateral  tube.     The  ring  D  must  then  be  connected  with  the  con- 
ductor of  an  electrical  machine,  by  a  chain   or  wire,  and  a  con- 
tinued discharge  of  electric  sparks  being  made  to  pass  between 
the  wires  CC,  the  stop-cock  next  the  bladder  must  be  opened, 
and  a  current  of  hydrogen  thrown  in,  which  inflaming,  heats  the 
capsule  and  diamond  to  white  heat,  and  the  diamond  taking  fire, 
will  burn  without  any  further  supply  of  hydrogen.     One  or  more 
small  diamonds  may  thus  be  exposed  to  combustion,  and  they 
will  continue  to  burn,  producing  a  strong  white  heat,  till  so  re- 
duced in  size  as  to  be  cooled  too  low  by  the  platina  capsule. 

265.  When  hydrogen  is  thus  employed  to  inflame  the  diamonds, 
a  little  water  will  be  formed  in  addition  to  the  products  of  the 
combustion  of  the  gem.     This  inconvenience  may  be  avoided  by 
using  the  flame  of  carbonic  oxide.  As,  however,  no  hydrogen  has 
been  found  to  exist  in  the  diamond,  it  is  better  to  use  that  gas  as 
the  heating  agent;  for  then  the  carbonic  acid  produced  by  the 
diamonds  will   be  unmixed  with  any  from  another  source,  and  it 
may  be  collected  and  its  quantity  exactly  ascertained.* 

266.  Carbonic  acid,  when  wanted  for  the  purpose  of  experi- 
ment, may,  however,  be  most  readily  obtained  by  decomposing 
the  combinations  of  this  acid  with  alkalies  or  earths.;  Thus  chalk 
or  marble,  (carbonate  of  lime,)  when  dropped  in  small  fragments 
into  diluted  sulphuric  or  muriatic  acid,  will  give  out  abundance 
of  this  gas.     Vinegar  or  almost  any  other  acid  may  be  used  in- 
stead of  those  just  mentioned  ;  as  the  affinity  of  carbonic  acid  for 
salifrable  bases  appears  to  be  weaker  than  that  of  most,  if  not  all 
other  acids.  Carbonic  acid  gas  may  be  collected  over  water,  which, 
however,  absorbs  a  large  portion  of  it,  even  at  common  pressures 
and  temperatures. 

By  what  means  is  a  temperature  of  ignition  first  communicated  to  tho 
diamond  in  this  apparatus  ? 

How  is  carbonic  acid  procured  for  purposes  of  chemical  experiment  ? 

*  Journal  of  Science,  ed.  at  R.  I.,  vol.  ix.  pp.  264,  265. 


106  CHEMISTRY. 

- 

2(57.  This  gas  is  destitute  of  colour  or  smell ;  but,  like  other 
acids,  if  has  a  sour  taste..  It  is  much  heavier  than  common  air, 
and  is  uninflammable,  extinguishing1  burning  bodies  which  are 
plunged  into  it.  Owing  to  its  great  specific  gravity,  it  may  be 
poured  from  one  vessel  to  another,  like  a  liquid;  and  will  re- 
main for  some  time  at  the  bottom  of  an  open  jar,  without  mix- 
ing with  the  atmospheric  air  above  it.  Hence  a  curious  effect 
may  be  produced,  by  placing  a  lighted  taper  at  the  bottom  of  a 
tall  glass  jar,  and  pouring  carbonic  acid -into  it,  which  will  imme- 
diately extinguish  the  taper,  just  as  if  water  had  been  poured 
over  it.  It  is  highly  deleterious  to  animals,  and  cannot  be  breath- 
ed without  the  utmost  danger,  as  appears  from  numerous  instances 
which  have  occurred  of  persons  who  have  lost  their  lives  by 
being  shut  up  in  a  close  chamber  with  braziers  or  chafing-dishes 
of  burning  charcoal,  or  by  descending  into  vats  at  the  bottom  of 
which  this  gas  had  been  produced  from  the  fermentation  of  vinous 
liquors.  It  is  also  sometimes  found  in  the  lower  parts  of  wells 
or  mines,  where  it  occasions  fatal  accidents ;  and  it  is  called  by 
miners  the  choke-damp.  It  is  discharged  from  the  surface  of  the 
water  of  some  natural  springs ;  from  caverns,  and  narrow,  deep 
valleys,  of  which  phenomena  an  account  will  be  found  in  another 
part  of  this  volume. 

268.  As  water  readily  takes  up  this  gas,  so  it  may  be  made  by 
pressure  to  absorb  a  large  quantity  of  it.     Thus  is  prepared  the 
liquor  called  soda  water,  which  in  general  consists  of  water  only, 
abundantly  impregnated  with  carbonic  acid,  by  pressure  and  agita- 
tion.    A  similar  fluid  is  formed  by  nature  in  the  bowels  of  the 
earth,  constituting  peculiar  mineral    waters,   as    those  of  Spa, 
Seltzer,  and  Pyrmont;  though  these  waters  appear  also  to  con- 
tain small  quantities  of  saline  matter  as  well  as  carbonic  acid.  , 
Water  impregnated  with  this  acid  reddens  paper  stained  with  a  blue 
colour  by  litmus ;  but  the  tint  thus  given  is  not  permanent,  like 
that  occasioned  by  the  stronger  acids. 

269.  Carbonic  acid  has  been  reduced  from  a  state  of  gas  to 
that  of  liquid  by  compression.   Mr.  Faraday  obtained  it  in  this 
form  by  disengaging  it  from  carbonate  of  ammonia  by  means  of 
sulphuric  acid,  in  a  glass  tube  hermetically  sealed,  one  end  of 
which  was  immersed  in  a  freezing  mixture.     The  liquid  acid, 
was  colourless,  and  floated  upon  the  sulphuric  acid  and   water 
contained  in  the  tube.    It  distilled  rapidly  over,  at  a  temperature 
below  the  freezing-point  of  water.     The  pressure  under  which 
this  fluid   was   formed  was  estimated  to  be  equal  to  thirty-six 
atmospheres. 

What  are  the  sensible  properties  of  this  gas  ? 

In  what  manner  may  its  unfitness  to  support  combustion  be  illustrated  ? 
What  fatal  effects  upon  animals  demonstrate  the  same  character? 
How  is  carbonic  acid  condensed  in  water  ? 
What  effect  has  water  thus  impregnated  on  vegetable  blues  ? 
At  what  temperature  and  pressure  may  carbonic  acid  assume  the  lio'-id 
form? 


CROCONIC  ACID.  107 

270. VCarbonic  acid  may  be  decomposed  by  the  action  of  the 
metal  potassium,  which  having  a  stronger  attraction  for  oxygen 
than  the  carbon  has,  when  it  is  heated  in  carbonic  acid  it  burns 
with  great  splendour;  charcoal  is  deposited,  and  an  oxide  of 
potassium  is  formed/  When  carbonic  acid,  obtained  by  burning  a 
diamond,  is  thus  decomposed,  the  carbon  produced  is  found  to  be 
exactly  equal  in  weight  to  that  of  the  diamond  consumed.  Car- 
bonic acid  may  also  be  decomposed  by  hydrogen  and  other  bodies ; 
but  phosphorus  when  heated  in  this  gas  does  not  effect  its 
decomposition,  the  affinity  of  carbon  for  oxygen  being  apparently 
greater  than  that  of  phosphorus. 

271.  Besides  the  two  compounds  of  carbon  and  oxygen  which 
have  been  just  noticed,  there  are  two  if  not  three  more  bodies  of  an 
acid  nature  which  also  appear  to  be  constituted  of  the   same 
elements,  but  in  different  proportions.  '  These  are  the  oxalic,  the 
mellitio,  and  croconic  acids. 

272.  .Oxalic  add  is  a  production  of  nature,  being  contained  in 
the  state  of  a  salt,  combined  with  potash,  in  wood-sorrel,  (Oxalis 
acctosella,}  common  sorrel,  (Ititmex  acetosa,}  and  in  several  species 
of  lichens.     It  may  likewise  be  procured  artificially,  by  the  action 
of  nitric  acid  on  sugar.    Bergrhann,  ascertained  it  to  be  a  peculiar 
kind  of  acid,  and  it  was  long  supposed  to  be,  like  most  of  those 
derived  from  vegetables,  a  compound  of  carbon  and  hydrogen 
with  oxogen  ;  but  Dobereiner  conjectured  it  to  consist  of  carbon 
and  oxygen  only,  as  is  now  generally  admitted.    When  obtained 
from  the  oxygenation  of  sugar,  or  from  the  decomposition  of  any 
of  its  salts,  it  forms  tetraedral  prismatic  crystals,  resembling  in 
their  general  appearance,  sulphate  of  magnesia,  (Epsom  salt;) 
and  as  it  is  a  powerful  poison,  many  fatal  accidents  have  been 
occasioned  by  its  being  mistaken  for  that  salt.   In  the  crystalline 
state,  the  oxalic  is  a  hydrated  acid,  containing  a  definite  portion 
of  water,  which  cannot  be  separated  from  it,  without  causing  its 
decomposition. 

273.  Mellitic  acid  is  of  mineral  origin,  being  found  in  combina- 
tion with  alumine  in  the  mellite  or  honey-stone. 

274.  Croconic  acid,  which  was  discovered  a  few  years  ago  by 
M.  Gmelin,  is  an  artificial  product,  the  nature  of  which  has  not 
been   properly    ascertained ;   but  it  appears  to   be   a   compound 
analogous  with  the  two  preceding  acids ;  but  differing  from  them 
in  the  relative  proportions  of  its  constituents. 

275.  The  following  are  the  respective  quantities  of  carbon  and 
oxygen  in  the  several  compounds  of  those  bodies,  according  to 
Mitscherlich : 

By  what  reagent  may  it  be  decomposed  ? 

What  other  acid  compounds  of  carbon  and  oxygen  exist  ? 

What  is  the  natural  source  from  which  oxalic  acid  is  obtained  ? 

What  is  its  crystalline  form  ? 

What  peculiar  property  does  it  possess  ? 

For  what  salt  has  it  been  often  mistaken  ? 


108  CHEMISTRY. 

Carbonic  acid  =100  Carbon  -f-  265.23  Oxygen. 
Oxalic  acid  =  100  Carbon  -j-  198.92  Oxygen. 
Carbonic  oxide  =  100  Carbon  +  132.615  Oxygen. 
Mellitic  acid  =  100  Carbon  -f-  99.46  Oxygen.* 

276.  With  chlorine  carbon  unites  in  three  proportions. )  The 
Protochloride  of  carbon  may  be  obtained  by  passing  the  vapour  of 
the  perchloride  through  a  red-hot  tube  containing  fragments  of 
rock  crystal,  to  increase  the  heated  surface,  and  thus  a  portion  of 
chlorine  is  driven  off,  and  the  protochloride  is  formed.     It  is  a 
limpid,  colourless  liquid,  which  does  not  become  congealed  at 
zero  of  Fahrenheit,  and  is  volatilized  at  about  165°.  Its  specific  gra- 
vity is  1.55.     It  is  insoluble  in  water,  but  mixes  readily  with 
alcohol,  ether,  and  oils.    It  dissolves  chlorine,  iodine,  sulphur,  and 
phosphorus.     It  is  not  combustible  unless  held  in  the  flame  of  a 
lamp,  to  which  it  communicates  a  yellow  tinge,  and  gives  off 
much  smoke,  mixed  with  fumes  of  muriatic  acid. 

277.  Perchloride    of  carbon  may  be  formed  by  exposing  car- 
buretted  hydrogen  gas,  mixed  with  a  great  excess  of  chlorine,  to 
the  action  of  light.     The  perchloride  thus  obtained,  is  a  transpa- 
rent, colourless,  crystalline  substance,  having  no  taste,  but  an 
odour  resembling  that  of  camphor.  Its  specific  gravity  is  about  2; 
it  is  a  non-conductor  of  electricity,  and  powerfully  refracts  light. 
It  is  volatile  at  low  temperatures,  dissolves  at  320°,  and  boils  at 
350°  Fahrenheit,  and  it  maybe  distilled  without  becoming  decom- 
posed, its  vapour  again  condensing  into  crystals  as  it  cools.  It  is  not 
readily  combustible,  but  burns  with  a  red  flame,  when  held  in  the 
flame  of  a  spirit-lamp,  becoming  decomposed,  and  forming  char- 
coal (which  flies  off  in  smoke)  and  muriatic  acid.     It  does  not 
dissolve  in  water,  but  readily  in  alcohol  and  ether,  and  also  in 
volatile  and  fixed  oils.    Potassium  burns  brilliantly  in  its  vapour, 
chloride  of  potassium  being  formed,  and  carbon  deposited. 

278.  There  is  a  third  compound  called  the  subchloride  of  car- 
bon, which  was  discovered  to  have  been  accidentally  formed,  in 
very  small  quantities,  in  a  manufactory  of  nitric  acid,  from  nitre 
and  oil  of  vitriol,  in  Sweden.     It  is  a  solid  crystalline  body,  vo- 
latilizing by  heat,  without  decomposition.    It  has  a  peculiar  smell, 
but  in  most  of  its  properties  resembles  the  perchloride,  containing 
however,  apparently,  a  smaller  quantity  of  chlorine  than  even  the 
protochloride. 

What  are  the  proportions  in  the  four  compounds  of  oxygen  and  carbon 
according  to  Mitscherlich? 

How  many  compounds  may  carbon  form  with  chlorine  ? 

What  are  the  properties  of  the  first  of  these  ? 

How  is  the  perchloride  of  carbon  obtained  and  what  are  its  properties  ? 

What  name  is  given  to  the  compound  of  iodine  and  carbon? 

In  what  manner  is  that  compound  produced? 

What  course  of  reactions  takes  place  in  this  process  ? 


*  Introd.  to  Chemistry,  vol.  i.  p.  412. 


SUBCARBURET  OF  HYDROGEN.  109 

279.  Iodide  of  carbon  may  be  obtained  by  mixing  a  saturated 
solution  of  iodine  in  alcohol,  with  a  strong  alcoholic  solution  of 
potash,  when  part  of  the  iodine  will  unite  with  the  potassium, 
and  the  oxygen  thus  disengaged  will  combine  with  the  hydrogen 
of  the  alcohol,  to  form  water ;  while  another  part  of  the  iodine 
combines  with  the  carbon  of  the  alcohol.     Iodide  of  carbon  is  a 
lemon-coloured  solid,  forming  bright  crystals,  having  a  sweetish 
taste,  and  an  odour  like  saffron.     Its  specific  gravity  is  nearly 
2.     It  does  not  dissolve  in  water,  but  readily  in   alcohol,   and 
still  more  so  in  ether.     It  also  dissolves  in  oils,  and  when  its 
solution  in  oil  of  lemon  is  exposed  to  light,  the  iodine  becomes 
decomposed,  and  carbon  and  iodine  are  deposited.     The  strong- 
acids  do  not  act  on  it,  nor  the  aqueous  solution  of  chlorine,  but 
chlorine  gas  decomposes  it.     It  evaporates  at  low  temperatures, 
and  dissolves  at  about  248°,  soon    becoming   decomposed,  and 
giving  out  vapours  of  iodine,  and  a  bright  charcoal.     When  this 
solid  iodide  is  mixed  and  distilled  with  perchloride  of  mercury, 
a  liquid  is  procured,  which  is  likewise  an  iodide  of  carbon,  which 
appears  to  consist  of  one  proportion  of  iodine,  and  one  of  carbon  ; 
while  the  solid  compound  contains  three  proportions  of  iodine, 
and  two  of  carbon,  the  latter,  therefore,  is  a  sesqui-iodide,  and 
the  liquid  an  iodide,  or  rather  a  protiodide  of  carbon. 

280.  Carbon    unites   with   hydrogen    in   several   proportions, 
forming  a  variety  of  compounds.     Subcarburet   of  hydrogen    is 
formed  at  the  bottom  of  pools  of  stagnant  water,  containing  ve- 
getable matter  in  a  state  of  decomposition.     It  is  a  gaseous  body, 
and  maybe  collected  in  an  inverted  bottle,  with  a  funnel  adapted 
to  it,  and  the  gas  thus  obtained  must  be  purified  by  passing  it 
through  lime-water,  or  a  solution  of  potash.    It  is  then  colourless 
and  transparent,  having  but  little  smell,  and  being  soluble  only  in 
a  minute  proportion  in  water.     It  is  inflammable,  burning  with  a 
yellow  flame,  and  giving  out  much  more  light  than  hydrogen. 
If  mixed  in  certain  proportions  with  atmospheric  air  or  oxygen 
gas,  a  violent  explosion  takes  place  on  the  introduction  of  flame. 
The  spontaneous  production  of  this  gas  frequently  takes  place  in 
coal-mines,    forming   what    the   miners    call   fire-damp,   which 
from  its  tendency  to  explode,  when  mixed  with  common  air,  has 
been  the  cause  of  numerous  dreadful  disasters. 

281.  As  the  mixture  of  these  gases  is  exploded  only  when  it 
comes  in  contact  with  flame,  various  methods  have  been  adopted  to 
furnish  the  labourers,  who  work  in  coal-mines,  with  light,  without 
incurring  the  risk  of  explosion.     With  this  view  was  invented  a 
kind  of  mill,  for  producing  continuous  circles  of  sparks,  by  the 

What  are  the  properties  of  iodide  of  carbon  ? 

What  is  the  composition  of  the  solid  and  what  of  the  liquid  iodide  of 
carbon  ?  What  chemical  denomination  properly  applies  to  each  ? 

How  is  subcarburet  of  hydrogen  formed  ? 

Enumerate  its  properties. 

Under  what  circumstances  will  subcarburet  of  hydrogen  and  common 
air  admit  of  an  explosion. 


110 


CHEMISTRY. 


action  of  flint  on  steel,  but  the  light  thus  given  out  is  too  incon- 
siderable to  be  of  much  service;  and  hence  different  kinds  ol 
safety-lamps  have  been  contrived,  the  most  efficient,  being  that 
of  Sir  H.  Davy,  the  principle  of  which  was  explained  in  the 
former  volume  of  this  work.* 

282.  The  accompanying  figure  represents  the  lamp 
as  recommended  for  general  use  by  its  inventor, 
and  is  taken  from  his  treatise  on  that  subject. 
«  is  a  cylinder  of  wire  gauze  with  a  double  top, 
securely  and  carefully  fastened  by  doubling  over 
to  the  brass  rim  Z>,  which  screws  on  the  lamp  c. 
The  whole  is  protected  and  rendered  convenient 
for  carrying  by  the  frame  and  ring  d.  The  small 
coil  of  platina  wire,  /?,  hung  within  the  wire  gauze 
cylinder  being  heated  by  the  flame  of  the  lamp, 
will  continue  to  glow  even  when  the  flame  quits 
the  wick  of  the  lamp,  on  being  introduced  into 
an  atmosphere  of  fire  damp,  thus  affording  a  feeble 
light  to  the  miner  who  would  otherwise  in  such 
cases  be  left  in  total  darkness.  When  made  of  plain 
wire  gauze  the  wire  should  be  not  less  than  one- 
sixtieth  of  an  inch  in  thickness,  and  the  number  to 
the  inch,  each  way  about  28  or  30. 

283.  Carburet  of  hydrogen  may  be  procured  by  heating  gently, 
over  a  lamp,  in  a  retort,  four  parts  of  sulphuric  acid,  and  one  of 
alcohol.     In  this  operation  the  mixture  becomes  black,  and  an 
abundant  disengagement  of  gas  takes  place,  which  may  be  collected 
over  water,   and  purified   by  agitating  it  with   lime-water,  or 
solution  of  potash.    This  gas  is  colourless,  and  when  pure  has  but 
little  smell.    It  is  inflammable,  burning  with  a  dense  white  flame, 
which  gives  much  light.     Water  absorbs  about  £  of  its  bulk  of 
this  gas,  and  it  is  also  absorbed  by  sulphuric  acid,  without  under- 
going decomposition.    If,  however,  these  bodies  be  placed  in  con- 
tact for  several  days,  one  volume  of  sulphuric  acid  will  absorb 
between  eighty  and  ninety  of  the  gas,  forming  a  peculiar  compound. 

284.  When  sulphur  is  heated  in  a  given  quantity  of  this  gas, 
carbon  is  separated,  and  twice  its  bulk  of  sulphuretted  hydrogen 
formed.     As  hydrogen  undergoes  no  change  of  volume  in  com- 
bining with  sulphur,  it  appears  that  carburetted  hydrogen  must 
contain  two  volumes  of  hydrogen  condensed  into  the  space  of  one  ; 
hence  this  gas  requires  for  its  complete  combustion  three  volumes 
of  oxygen,  and  the  product  will  be  water  and  two  volumes  of 
carbonic  acid.     This  gas  may  also  be  decomposed  by  passing  it, 
and  repassing  it  through  a  red-hot  tube  of  iron  or  earthen-ware, 

Explain  the  construction  of  Davy's,  safety  lamp  to  prevent  that  effect? 

How  is  carburet  of  hydrogen  obtained  ? 

What  are  the  sensible  and  chemical  properties  of  this  gas  ? 

How  is  it  decomposed  by  sulphur  ?    How  by  heat  ? 

*  See  Scientific  Class  Book,  pt.  i.  Pyronomics,  No.  144  and  145  p.  326. 


COMPOUNDS  OF  CARBON  AND  HYDROGEN.  Ill 

when  the  carbon  it  contains  is  deposited,  and  its  hydrogen  be- 
comes expanded  to  double  the  original  bulk. 

285.  This  gas  when  first  discovered,  in  1796,  was  termed  ole- 
fiant  gas,  from  its  property  of  forming  a  substance  like  oil  when 
added  to  chlorine.     If  equal  quantities  of  carburet  of  hydrogen 
and  chlorine  be  mixed  together,  a  diminution  of  bulk  takes  place, 
and  a  substance  is  produced,  having  the  appearance  of  oil,  but 
resembling  ether  in  its  general  properties.     It  is  a  liquid  which 
boils  at  152°  Fahrenheit,  and   its  specific  gravity  at  45°  is  1.22. 
It  consists  of  equal  volumes  of  chlorine  and  carburet  of  hydrogen, 
and  it  has  been  termed  hydrockloride  of  carbon. 

Olefiant  gas  also  combines  with  iodine  and  bromine,  to  form 
definite  compounds. 

286.  In  addition  to  the  gaseous  carburet  and  subcarburet  of 
hydrogen,  Dr.  Dal  ton  and  some  other  writers,  mention  a  third 
compound  of  carbon  and  hydrogen,  called  super-olefiant  gas,  as  it 
requires,  for   its   complete   combustion,  a   larger   proportion   of 
oxygen  than  the  olefiant  gas.    But  it  seems  uncertain  whether 
this  elastic  fluid  is  a  definite  chemical  compound,  or  merely  a 
mixture  of  the  preceding  inflammable  gases.    There  are,  however, 
several  other  combinations  of  carbon  and  hydrogen,  which  are, 
under   common  temperatures   and  pressures,   liquids   or   solids. 
Among  the  former  may  be  mentioned  two  liquids  obtained  by 
Mr.  Faraday,  from  the  fluid  matter  which  occurs  in  the  distillation 
of  whale-oil,  for  the  production  of  oil-gas,  one  of  which  is  the 
lightest  of  all  known  bodies,  except  gases,  its  specific  gravity 
being  0.602;    naphtha,  a  volatile,  inflammable  liquid,  obtained 
during  the  distillation  of  coal-tar,  and  also  occuring  in  some  parts 
of  the  world,  in  springs,  more  or  less  mixed  with  water ;  oil  of 
wine,  formed  during  the  preparation  of  sulphuric  ether ;  rectified  oil 
of  turpentine,  which  appears  to  be  very  similar  in  its  constitution 
to  naphtha ;  oil  of  lemon,  and  probably  other  essential  oils. 

287.  The   solid   compounds  of  carbon  and  hydrogen  include 
naphthaline,  a  crystalline  body,  which  occurs  in  the  distillation 
of    coal-tar ;    paraffin,   another   crystallizable   substance,   found 
among  the  products  of  the  destructive  distillation  of  wood ;   a 
kind  of  scaly  crystals  held  in  solution  by  oil  of  roses,  from  which 
they  may  be,  separated  by  exposure  to  a  low  temperature,  and  the 
crystals  may  be  freed  from  the  adhering  oil  by  pressure  between 
leaves  of  blotting-paper,  kept  very  cool ;  and  caoutchouc,  or  the 
substance  called  Indian  rubber. 

288.  There  is  a  circumstance  highly  deserving  of  attention 
with  regard  to  the  compounds  of  carbon  and  hydrogen  which  may 
here  be  noticed.     So  far  as  we  are  acquainted  with  the  atomic 

What  name  was  at  first  given  to  it  ? 

How  is  the  hydro-chloride  of  carbon  obtained  ? 

In  what  state  does  it  exist? 

What  are  its  composition  and  character? 

What  other  liquid  compounds  of  hydrogen  and  carbon  are  enumerated  ? 

What  solid  compounds  of  the  same  ingredients  are  known  to  chemists? 


112  CHEMISTRY. 

constitution  of  these  bodies,  they  appear  to  be  susceptible  of  ar- 
rangement in  classes  or  sections,  each  division  consisting  of  a 
given  number  of  carburets  of  hydrogen,  agreeing  with  each  other 
in  the  relative  proportions  of  their  constituents,  but  differing  more 
or  less  in  their  properties  and  modes  of  action.  As  examples  of 
the  compounds  in  question,  may  be  specified  olefiant  gas,  paraffin, 
Faraday's  volatile  liquid  carbo-hydrogen,  and  oil  of  wine,  in  all 
which  carbon  and  hydrogen  exist  in  equal  proportions;  and  oil  of 
lemon,  oil  of  turpentine,  and  a  liquid  called  camphogene,  or  the 
basis  of  camphor,  in  which  the  quantity  of  carbon  is  to  that  of  hy- 
drogen as  5  to  4.  Other  instances  of  a  corresponding  nature  will 
be  noticed  in  treating  of  phosphorus. 

289.  Carbon  unites  with  nitrogen  to  form  a  remarkable  com- 
pound called  cyanogen,  or  the  basis  of  prussic  or  hydrocyanic 
acid,  which,  by  its  combination  with  oxide  of  iron  produces  Prus- 
sian blue.     It  is  properly  a  bicarburet  of  nitrogen,  and  in  order  to 
obtain  it,  it  is  necessary  first  to  form  the  salt,  formerly  called  prus- 
siate  of  mercury,  but  now  cyanuret  of  mercury.  This  is  composed 
by  boiling  red  oxide  of  mercury,  with  twice  its  weight  of  Prussian 
blue,  in  a  sufficient  quantity  of  water,  when  those  bodies  will  unite 
to  form  a  crystallizable  compound.   The  cyanuret  of  mercury,  thus 
obtained,  after  having  been  carefully  dried,  at  a  temperature  below 
212°  Fahrenheit,  must  be  heated  in  a  small  glass  tube,  when  it 
•becomes  black,  and  liquefies,  and  is  at  length  decomposed.    The 
mercury  becoming  condensed  in  the  cold  part  of  the  tube,  and  a 
gas  being  at  he  same  time  evolved,  which  must  be  collected  over 
mercury.     This  is  cyanogen,  which  at  the  usual  temperature  and 
pressure  of  the  atmosphere,  is  a  permanently  elastic  fluid,  though, 
as  elsewhere  stated,  it  has  been  condensed  to  the  liquid  state 
by  Mr.  Faraday. 

290.  It  has  a  peculiar  pungent  odour,  resembling  that  of  bitter 
almonds,  and  it  is  destitute  of  colour.     It  is  inflammable,  burning 
in  contact  with  air,  with  a  fine  purple  flame  ;  but  any  burning  body, 
as  a  lighted  match,  plunged  into  it  becomes  extinguished.    It  dis- 
solves in  water,  and  more  largely  in  alcohol.     The  aqueous  solu- 
tion reddens  vegetable  blues,  and  according  to  Vauquelin,  it  be- 
comes  spontaneously  decomposed,  and  converted  into  carbonic 
and  hydrocyanic  acids,  ammonia,  a  peculiar  acid  called  the  cyanic, 
and  a  brown  substance  containing  carbon;  the  ammonia  combines 
with  the  acids,  and   the  carbonaceous  compound    is   deposited. 
These  phenomena  are  owing  to  the  reaction  of  the  elements  of 
cyanogen  upon  those  of  water.     When  cyanogen  is  mixed  with 
oxygen,  it  may  be  exploded  by  the  electric  spark.    If  one  volume 
of  this  gas  and  two  of  oxygen  be  detonated  over  mercury,  the 

What  remarkable  circumstance  distinguishes  the  various  compounds  of 
carbon  and  hydrogen  ? 

What  compound  results  from  the  union  of  carbon  and  nitrogen? 
What  is  the  true  nature  of  cyanogen  ? 
How  is  it  obtained  ? 
What  are  its  properties  ? 


PRUSSIC  ACID BORON.  113 

product  will  consist  of  two  volumes  of  carbonic  acid,  and  one 
of  nitrogen. 

291.  Cyanogen,  though  a  compound,  enters  into  combination 
with  elementary  bodies,  in  a  manner  very  similar  to  the  mode  of 
action  of  oxygen  and  chlorine.  '/  Thus,  like  oxygen,  it  combines 
with  several  of  the  metals,  constituting  compounds,  which  might 
be  termed  cyanides,  though  they  are  generally  called  cyanurets, 
and  as  chlorine  forms  with  hydrogen  muriatic  acid,  so  cyanogen, 
combined  with  hydrogen  forms  hydrocyanic  or  prussic  acid. 

292.  The  chemical  properties  of  this  acid  may  here  be  described. 
It  may  be  obtained  by  heating,  in  a  tubulated  glass  retort,  three 
parts  of  cyanuret  of  mercury,  with  two  parts  by  weight  of  concen- 
trated muriatic  acid.     A  vapour  rises,  consisting  of  water  and  the 
muriatic  and  prussic  acids,  the  former  of  which  may  be  separated 
by  passing  the  vapour  through  a  narrow  tube,  containing  frag- 
ments of  marble.     It  must  then  be  passed  over  dry  chloride  of 
calcium,  and  condensed  in  a  vessel  surrounded  by  ice. 

293.  The  prussic  acid  thus  obtained,  is  a  limpid  fluid  with  a 
strong  smell,  like  th^at  of  laurel  water  or  bitter  almonds,  and  an 
acrid  taste.     It  is  extremely  deleterious,  proving  destructive  to 
animal  life,  in  a  small  quantity,  when  either  swallowed  or  inhaled, 
and  therefore  the  utmost  care  should   be  taken  in  preparing  it  to 
avoid  breathing  the  vapour,  which,  when  much  diluted  with  atmo- 
spheric  air,   will   cause   giddiness   and   headache.      This   acid 
volatilizes  so  rapidly,  as  to  freeze  in  consequence  of  the  cold  pro- 
duced by  its  evaporation.     Its  specific  gravity  compared  with  hy- 
drogen is  13.5,  100  cubic  inches  weighing  28.593  grains.     It  con- 
sists of  one  volume  of  cyanogen,  and  one  of  hydrogen.    This  acid 
slightly  reddens  litmus  paper,  and  it  combines  with  alkalies  and 
other  bases  to  form  salts ;  but  its  affinities  are  so  feeble,  that  these 
compounds  are  decomposed  even  by  carbonic  acid.      It  dissolves 
in  any  proportion  in  water  and  alcohol ;   and  it  is  occasionally 
used  as  a  powerful  medicine,  and  therefore  in  small  doses,  chiefly 
as  a  sedative,  in  cases  of  phthisis  pulmonalis. 

Boron. 

294.  This  substance  is  usally  obtained  by  heating  together,  in 
a  copper  or  iron  tube,  one  part  of  boracic  acid,  formerly  called  the 
fiedative  salt  of  Homberg,  previously  melted  and  powdered,  and 
two  parts  of  potassium ;  when  the  temperature  being  raised  till  the 
tube  becomes  red,  the  metal  attracts  the  oxygen  from  the  acid, 
and  the  boron  may  thus  be  procured,  in  the  form  of  a  brown  pow- 
der, having  neither  taste  nor  smell,  and  insoluble  in  water,  alcohol, 

What  results  from  the  detonation  of  cyanogen  and  oxygen  ? 

What  analogy  exists  between  cyanogen  and  oxygen  or  chlorine  ? 

Give  examples  of  this  analogy. 

What  name  is  given  to  its  compound  with  hydrogen  ? 

What  are  the  properties  of  hydrocyanic  acid  ? 

What  is  its  composition  ? 

How  is  boron  procured  ? 


114 


CHEMISTRY. 


ether,  or  oil,  even  when  heated.  It  is  permanent  in  the  air  at  com- 
mon temperatures,  and  is  infusible.  It  is  a  non-conductor  of 
electricity ;  and  its  specific  gravity  is  more  than  twice  that  of 
water.  It  does  not  decompose  water  when  heated  to  176°  of 
Fahrenheit.  '  At  low  temperatures,  boron  remains  unchanged  in 
atmospheric  air  or  oxygen  ;  but  at  a  temperature  of  600°  of  Fahren- 
heit it  burns  with  brilliancy,  becoming  united  with  oxygen,  and 
forming  boradc  acid. 

295.  By  means  of  an  apparatus  represented  by  the  annexed  en 
graving,  Dr.  Hare  has  succeeded  in  evolving  boron  by  the  reaction 
of  potassium  with  vitrified  boracic  acid,  in  vacuo,  without  en- 
countering the  evil  of  any  explosive  action,  to  which  the  process, 
as  heretofore  conducted  in  pleno,  has  been  found  liable. 


"  A  circular  brass  plate,  is  prepared,  like  the  plate  of  an  air  pump, 
so  as  to  produce,  with  any  suitable  receivers  properly  ground,  an 
air-tight  juncture.  It  is  supported  on  the  upper  end  of  a  hollow 
brass  cylinder,  B,  with  the  bore  of  which  it  has  a  corresponding 

What  are  its  properties  ?    At  what  temperature  is  its  combustion  effected? 
What  is  the  result  of  that  process  ? 


PROCESS  FOR  THE  EVOLUTION  OF  BORON.       115 

aperture.  The  brass  cylinder  is  about  three  inches  in  diameter, 
and  six  inches  in  height,  being  inserted  at  its  lower  end  into  a 
block  of  wood  as  a  basis.  This  cylinder  receives  below,  a  screw, 
which  supports  a  copper  tube,  C,  of  about  two  inches  in  diameter, 
so  as  to  have  its  axis  concentric  with  that  of  the  cylinder,  and  to 
extend  about  four  inches  above  the  plate.  The  copper  tube,  thus 
supported,  is  closed  at  the  upper  termination  by  a  cup  of  copper, 
of  a  shape  nearly  hemispherical,  and  soldered  at  the  upper  edge, 
to  the  edge  of  the  tube ;  so  that  the  whole  of  the  cavity  of  the 
cup,  is  within  that  of  the  tube.  Hence  the  bottom  of  the  cup  is 
accessible  to  any  body,  not  larger  than  the  bore  of  the  tube,  with- 
out any  communication  arising  between  the  cavity  of  the  tube,  and 
that  of  any  receiver  placed  upon  the  plate,  over  the  cup  and  tube, 
as  in  the  figure. 

"  Into  the  side  of  the  cylinder  supporting  the  plate,  a  valve  cock 
is  screwed,  by  means  of  which,  and  a  flexible  leaden  tube,  a  com- 
munication with  an  air  pump  is  opened,  or  discontinued,  at  pleasure. 

44  The  cup  being  first  covered  with  a  portion  of  the  vitrified  boracic 
acid,  as  anhydrous  as  possible,  and  finely  pulverized,  the  potas- 
sium is  introduced,  and  afterwards  covered  with  a  further  portion 
of  the  same  acid,  two  parts  of  the  potassium  being  used  for  one  of 
the  acid.  A  large  glass  receiver  is  now  to  be  placed  on  the  plate, 
secured  by  rods  A,  A,  concentric  with  the  tube  and  cup  ;  from  the 
heat  of  which  the  glass  is  to  be  protected  by  a  bright  cylinder  of 
sheet  brass,  S,  placed  around  it  so  as  to  be  concentrical  with  the 
receiver  and  tube. 

296. "  The  apparatus  being  so  prepared,  and  the  receiver  exhausted 
of  air  by  means  of  the  air  pump,  an  incandescent  iron  is  introduced 
through  the  bore  of  the  tube,  so  as  to  touch  the  bottom  of  the  cop- 
per cup.  In  a  short  time  a  reaction  commences,  which  aiding  the 
influence  of  the  hot  iron,  renders  the  cup  and  its  contents  red-hot. 
A  deep  red  flame  appears  throughout  the  mass,  after  which  the 
reaction  lessons,  and  the  heat  declines. 

44  When  the  cup  has  become  cold,  the  air  is  admitted  into  the  re- 
ceiver, and  the  contents  are  washed  with  water.  If  any  of  the 
acid  has  escaped  decomposition,  it  may  be  removed  by  boiling  the 
mass  with  a  solution  of  potash  or  soda.  After  this  treatment  and 
due  desiccation  a  powder  will  remain,  having  the  characteristic 
colour  and  properties  of  boron." 

297.  Boracic  acid,  which  is  used  in  medicine,  is  generally  ob- 
tained from  the  decomposition  of  borax  by  sulphuric  acid.  It  may 
be  crystallized  in  the  form  of  small  shining  plates  or  scales,  in 
which  state  it  is  combined  with  water,  constituting  a  hydrate; 
but  by  exposure  to  a  strong  red  heat,  it  melts  into  a  hard  trans- 

farent  glass ;    and  at  a  white  heat  it  becomes  slowly  sublimed, 
n  the  state  of  hydrate  its  specific  gravity  is  1.48,  and  in  that  of 
glass  about  1.8.     It  dissolves  sparingly  in  water,  and  the  solution 

Describe  Dr.  Hare's  method  of  obtaining  boron. 

What  changes  m  ly  boracic  acid  be  made  to  undergo  by  heat  I 


116  CHEMISTRY. 

reddens  vegetable  blues,  like  other  acids ;  but  when  applied  to 
paper  wetted  with  infusion  of  turmeric,  it  acts  like  an  alkali,  ting- 
ing it  brown.  The  solution  of  boracic  acid  in  alcohol  burns  with 
a  green  flame.  This  acid  is  found  naturally  in  the  hot  springs  of 
Sasso,  in  Tuscany,  and  also  in  the  Lipari  Islands ;  and  it  like- 
wise occurs  combined  with  magnesia  in  the  mineral  called 
boracite. 

298.  Boron  may  be  made  to  combine  with  chlorine,  by  passing 
that  gas  over  charcoal  and  boracic  acid  in  a  state  of  incandescence. 
The  chloride  of  boron  thus  formed,  is  a  gas,  which  may  be  collected 
over  mercury.     It  is  colourless,  heavier  than  air,  and  emits  fumes 
when  exposed  to  air;  but  does  not  undergo  decomposition  when 
strongly  heated. 

299.  A  gaseous  acid  called  the  lorofluoric  acid,  was  obtained  by 
the   French    chemists,    Gay   Lussac   and   Thenard,   by   heating 
together  vitrified  boracic  acid  and  fluor  spar  (fluoride  of  calcium.) 
In  this  process  the  oxygen  of  the  boracic  acid  appears  to  enter  into 
union  with  the  calcium  of  the  spar,  forming  oxide  of  calcium,  and 
the  fluorine  being  thus  set  free,  unites  with  the  boron  to  form  the 
acid  gas.     It  is  colourless,  but  has  a  powerful  smell,  like  muriatic 
acid  ;  is  highly  deleterious  when  respired,  and  extinguishes  flame. 
It  has  an  acid  taste,  and  strongly  reddens  vegetable  blues.     It 
instantly  carbonizes  animal  and  vegetable  substances,  but  it  has 
no  effect  upon  glass;    thus  exhibiting  a  striking  dissimilarity 
with  the  hydrofluoric  acid.      When  mixed  with  oxygen  gas  it  is 
not  decomposed,  but  it  powerfully  attracts  moisture;  and  hence 
when  bubbles  of  it  are  allowed  to  escape  into  the  air,  a  dense 
white  cloud   is  produced,  arising  from   the   combination  of  the 
borofluoric  acid  with  the  hygrometric  water  of  the  atmosphere. 

Silicon. 

300.  This  is  a  peculiar  solid  body,  hitherto  undecomposed,  and 
therefore  considered  as  elementary,  which  in  the  state  of  combi- 
nation with  oxygen  is  one  of  the  most  abundant  substances  in 
nature.     Sir  H.  Davy  appears  to  have  effected  the  decomposition 
of  the  oxide,  or  rather  acid  of  silicon,  (siliceous  earth,)  by  means 
of  Galvanism ;  but  he  was  unable  to  collect  the  product  of  the 
operation  so  as  to  ascertain  its  properties. 

301.  Berzelius  separated  the  silicon  from  its  acid  by  means  of 
Iron,  and  his  experiments  were  repeated  by  Professor  Stromeyer ; 
and   the  former  at  length  succeeded  in  procuring  silicon  in  an 
uncombined  state.     The  process  which  he  recommends  is  r.ot 

Where  is  it  found  in  nature  I 

What  compound  does  it  form  with  chlorine  ? 

What  are  its  properties  ? 

How  is  borofluoric  acid  obtained  ? 

What  effect  has  borofluoric  acid  on  vegetable  and  animal  substances? 

What  effect  has  it  on  atmospheric  air  ? 

What  is  the  true  chemical  character  of  siliceous  earth  ? 

Who  first  procured  silicon  so  as  to  exhibit  it  in  a  separate  state  ? 


SILICIC  ACID.  117 

difficult,  and  its  efficacy  depends  on  the  affinity  of  potassium  for 
oxygen,  which  it  attracts  when  the  double  fluate  of  silica  and 
potassa  is  heated  nearly  to  a  red  heat  in  a  glass  tube  closed  at  one 
end ;  fragments  of  potassium  being  then  introduced  into  the  tube 
and  made  to  mix  with  the  fused  salt,  heat  is  again  applied,  and 
a  feeble  detonation  ensues.  The  mass  must  then  be  left  to  cool,  and 
the  product  being  thrown  into  cold  water,  hydrogen  is  disengaged 
from  the  action  of  the  siliciuret  of  potassium,  which  becomes  con- 
verted into  hydruret  of  silicon  and  potassa. 

302.  The  hydruret  thus  obtained  being  heated  in  a  platina  cruci- 
ble, the  hydrogen  will  be  driven  off,  and  the  silicon  will  remain, 
in  the  form  of  a  snuff-coloured  or  nut-brown  powder.    It  does  not 
burn  either  in  air  or  oxygen  gas ;  neither  is  it  fused  or  at  all  changed 
by  exposure  to  powerful  heat. 

303.  Silicic  acid. — Silicon,  though  thus  incombustible,  may  be 
indirectly  united  with  oxygen  by  various  methods,  forming,  as 
already  observed,  the  body  known  as  siliceous  earth.     The  com- 
bination may  be  effected  by  mixing  silicon  with  dry  carbonate  of 
potassa,  and  exposing  it  to  red  heat,  when  the  oxygen  of  the  car- 
bonic acid  will  unite  with  the  silicon,  and  a  combination  of  silicic 
acid  and  potassa  will  be  formed.     If  fused  nitrate  of  potassa  be 
used  instead  of  the  carbonate,  no  effect  will  take  place ;  though 
the  addition  of  a  little  dry  carbonate  of  potassa  occasions  imme- 
diate deflagration. 

301.  This  peculiar  phenomenon  is  owing  to  the  influence  of  the 
alkali,  which  having  a  strong  affinity  for  silica,  disposes  the  silicon 
to  combine  with  the  oxygen  of  the  carbonic  acid,  in  which  the 
union  between  carbon  and  oxygen  is  but  weak.  Nitric  acid,  on 
the  contrary,  being  a  very  strong  acid,  entirely  prevents  the  alkali 
of  the  nitrate  from  acting  on  the  silicon ;  unless  the  substances 
be  heated  to  whiteness,  and  then  the  nitric  acid  becoming  decom- 
posed, the  silicon  will  attract  its  oxygen,  and  rapid  combustion 
will  take  place. 

305.  When  silicon  is  heated  with  caustic  potassa  or  soda,  it 
burns  in  the  oxygen  of  the  water  which  they  contain,  forming 
siiica.  This  substance  may  be  found  nearly  pure  in  colourless 
rock  crystal  or  quartz  ;  and  in  flint  the  earth  is  only  combined 
with  a  little  iron.  In  order  to  obtain  silica  in  a  state  of  absolute 
purity,  rock  crystal  may  be  reduced  to  powder  by  heating  it  red- 
hot,  and  throwing  it  into  water,  and  then  bruising  it  in  a  mortar  : 
one  part  of  this  powder  is  to  be  fused  in  a  silver  crucible,  with 
three  times  its  weight  of  potassa,  and  the  mass  thus  formed  being 
dissolved  in  water,  muriatic  acid  is  to  be  dropped  into  the  solution 
so  long  as  any  precipitate  is  produced  ;  the  liquid  is  then  to  be 
poured  off,  and  the  precipitate,  which  is  acid  of  silicon,  must  be 
repeatedly  washed  with  distilled  water,  and  then  dried. 

What  process  does  Berzelius  recommend  for  procuring  silicon? 
How  may  silicic  acid  be  formed  ?     How  is  the  process  accounted  for  ? 
What  happens  when  silicon  is  heated  in  caustic  potash  ? 
How  is  pure  silica  obtained  ? 


118  CHEMISTRY. 

306.  Silica  thus  obtained  is  a  white,  tasteless  powder,  feeling 
harsh  when  rubbed  between  the  fingers.     It  is  nearly  insoluble  in 
water,  and  probably  in  all  acids,  except  the  hydrofluoric.     It  is 
infusible  alone  before  the  blowpipe,  unless  the  flame  be  fed  with 
oxygen  gas,  when  it  melts  with  difficulty  into  a  colourless  globule. 
Though   water  has  no  action  on  it  after  it  has  been  dried,  yet, 
according  to  Kirwan,    when  first  precipitated  and  still  moist,  it 
dissolves  in  a  thousand  parts  of  distilled  water;  and  it  is  certain 
that  nature  has  some  process  for  the  solution  of  this  substance, 
since  it  is  found,  though  in  minute  proportions,  in  the  water  of 
some  hot  springs,  as  the  Geysers  in  Iceland.   When  first  prepared 
and  minutely  divided,  it  readily  dissolves  in  solutions  of  potassa 
or  soda ;  but  ammonia  has  no  effect  on  it. 

307.  When  silica  is  fused  with  a  large  portion  of  potassa,  a 
compound  is  produced  readily  soluble  in  water,  forming  the  liquor 
silicum,  liquor  of  flints,  of  old  writers.     Professor  Seigling,  of 
Erfurdt,  having  prepared  this  liquor  with  aJarge  quantity  of  water 
and  of  alkali,  he  suffered  it  to  stand  for  eight  years  in  a  glass  vessel, 
covered  with  paper,  when  crystals  of  salts  of  potash  were  formed 
at  the  bottom  of  the  vessel,  and  the  remaning  liquid,  about  two 
ounces,  was  covered  by  a  transparent  crust,  consisting  partly  of 
carbonate  of  potash,  and  partly  of  crystallized  silica :  the  latter 
so  hard  as  to  strike  fire  with  a  steel. 

308.  When  silica  is  fused  with  a  small  proportion  of  potash  or 
soda,  without  water,  the  product  is  that  useful  substance  glass. 
In  the  manufacture  of  glass  a  variety  of  other  substances  are  oc- 
casionally added  to  the  silica  and  alkali,  for  various  purposes  : 
among  these  may  be  mentioned  black  oxide  of  manganese,  which 
renders  glass  colourless,  and  improves  its  transparency ;  litharge 
or  oxide  of  lead,  used  in  making  what  is  called  flint  glass;  lime, 
which  is  added  to  the  ingredients  for   crown  or  the  best  win- 
dow glass ;  and  boracic  acid  or  borax,  employed  in  making  arti- 
ficial gems.     White   arsenic,   nitre,  brick  clay,  and   other  sub- 
stances are  sometimes  added  to  improve  the  quality  of  glass  ; 
or  in  the  coarser  kinds,  to  increase  the  quantity. 

309.  Silica  was  long  classed  among  the  earths  from  which  it 
differs  decidedly,  in  not  forming  salts  with  acids  ;  the  hydrofluoric 
acid,  as  already  observed,  being  the  only  one  with  which  it  enters 
into  combination.     Hence  it  appears  that' silica  cannot  act  the 
part  of  a  base  like   the   alkalies,    earths,  and   metallic  oxides. 
With  several  of  these,  however,  it  is  found  combined  in  various 
minerals,  and  therefore  as  to  its  mode  of  action  it  has  an  obvious 
analogy  with  acids,  and  some  chemists  have  given  it  the  name  of 
silicic  acid,  instead  of  silicic  oxide  :  and  to  the  compounds  formed 
by  its  union  with  several  earths  and  metallic  oxides,  they  have 

What  are  its  prominent  properties  ? 

Where  does  it  exist  in  natural  solution  ? 

How  is  the  liquor  of  flints  obtained  ? 

Into  what  artificial  product  does  silica  enter? 

In  what  respect  does  silica  differ  from  other  earths  ? 


PHOSPHORUS.  119 

applied  the  designation  of  silicates;  and  thus  glass  might  be  con- 
sidered as  a  silicate  of  potassa  or  soda. 

310.  Among  the  combinations  of  silicon  with  the  elementary 
substances,  may  be  mentioned  those  that  it  forms  with  chlorine 
and  with  fluorine.     When  silicon  is  heated  in  chlorine,  as  when 
a  current  of  that  gas  is  made  to  pass  over  red-hot  silicon  in  a 
porcelain  tube,  a  fuming  liquid  is  obtained  of  a  yellow  colour, 
extremely  volatile  and  irritating,  which  when  exposed  to  moisture 
becomes  decomposed  forming  muriatic  acid  and  silica.  This  is  the 
chloride  of  silicon.    When  potassium  is  heated  in  the  vapour  of  this 
chloride,  it  burns,  with  the  production  of  siliciuret  and  chloride 
of  potassium. 

311.  Silicofluoric  acid,  or  fluoride  of  silicon,  may  be  made  by 
distilling  in  a  retort  three  parts  of  fluor  spar  and  two  of  powdered 
silica,  with  an  equal  weight  of  sulphuric  acid,  when  a  gas  will 
be  produced  which  may  be  collected  over  mercury.     Water  must 
be  carefully  excluded  in  this  operation,  therefore  the  apparatus  must 
be  made  quite  dry.     Silicofluoric  acid  is  a  colourless  gas,  having 
a  pungent  smell,  much  like  that  of  muriatic  acid,  and  a  very  sour 

ste.  It  is  more  than  3^  times  the  weight  of  common  air.  It 
extinguishes  the  flame  of  a  taper,  and  forms  white  fumes  when 
exposed  to  moisture,  being  readily  absorbed  by  water;  from 
which,  however,  silica  is  precipitated,  hydrofluoric  acid  being 
produced.  If  the  beak  of  a  retort  from  which  this  gas  is  issuing 
be  plunged  beneath  water,  it  soon  becomes  choked  by  the  abundant 
deposition  of  hydrated  silica,  which  sometimes  forms  tubes 
through  the  water,  by  which  the  gas  passes  off  into  the  air. 

Silicon  likewise  unites  with  sulphur,  and  with  several  of  the 
metals,  especially  platina  and  iron. 

Phosphorus. 

312.  This  body  being  highly  inflammable,  and  consequently 
having  a  strong  affinity  for  oxygen,  seldom  occurs  naturally  ex- 
cept in  combination  with  that  element,  constituting  phosphoric 
acid  united  with  some  base,  in  the  state  of  a  salt.     It  is  thus 
found  in  the  bones  of  animals,  the  denser  parts  of  which  consist 
principally  of  phosphate  of  lime,  or  the  combination  of  lime  with 
phosphoric  acid,  and  from  the  decomposition  of  this  earthy  salt 
phosphorus  is  procured.    The  usual  process  is  to  digest  a  quantity 
of  calcined  or  burnt  bones,  reduced  to  powder,  in  half  their  weight 
of  strong  sulphuric  acid.     The  phosphate  of  lime  is  thus  decom- 
posed, and  the  phosphoric  acid,  after  being  separated  from  the 
lime,  undergoes  a  further  decomposition  by  being  mixed  with 
powdered   charcoal,   and    strongly  heated  in  an   earthen   retort, 

How  is  silicon  made  to  combine  with  chlorine  ? 
How  can  it  be  combined  with  fluorine  ? 
Enumerate  the  properties  of  fluoride  of  silicon  ? 
With  what  metals  is  silicon  capable  of  combining  ? 
In  what  combination  is  phosphorus  found  in  nature  ? 
What  is  the  usual  process  for  procuring  phosphorus  ? 


120  CHEMISTRY. 

when  the  charcoal  will  combine  with  the  oxygen  of  the  acid,  and 
the  phosphorus  passing  over,  may  be  received  in  a  vessel  of 
water,  under  the  surface  of  which  the  beak  of  the  retort  must 
be  plunged.  The  process  is  troublesome,  and  requires  much  atten- 
tion on  the  part  of  the  operator. 

313.  Phosphorus  thus  obtained  is  a  flesh-coloured,  slightly- 
transparent  solid,   nearly  the   consistence   of  wax ;   which,   on 
account  of  its  inflammability,  must  be  preserved  under  water. 
If  heated  in  water,  it  melts  at  about  110°  Fahrenheit,  and  boils  or 
becomes  evaporated  at  550°.     When  exposed  to  the  atmosphere 
at  common  temperatures,  it  emits  a  light  smoke,  and  a  peculiar 
odour,  resembling  that  of  garlic,  giving  out  in  the  dark  a  beauti- 
ful pale-green  light.   In  this  case  it  undergoes  a  slow  combustion. 
It  is  soluble  in  essential  oils,  and  communicates  to  them  the  pro- 
perty of  shining   in  the  dark.     In  pure  nitrogen  gas  it  is   not 
luminous,  undergoing  no  alteration  at  any  temperature.     But  it 
appears  that  the  smallest  possible  quantity  of  oxygen  will  suffice  to 
produce  some  degree  of  combustion  ;*  for  it  will  burn,  or  at  least 
give  out  light  in  the  exhausted  receiver  of  an  air-pump.     Phos- 
phorus may  be  set  on  fire  by  friction  at  a  low  temperature,  and  at 
about  100°  it  takes  fire,  and  burns  with  intense  brilliancy,  throw- 
ing off  abundance  of  white  fumes. 

314.  This  substance  combines  with  oxygen  in  different  propor- 
tions.   Oxide  of  phosphorus  is  a  white  substance  with  which  phos- 
phorus becomes  covered  when  kept  for  some  time  under  water.  It 
is   very   inflammable,  and  may  be  used  in   making  phosphoric 
match-boxes.     For  this  purpose  a  piece  of  phosphorus  must  be 
introduced  into  a  small  phial,  melted  slowly  by  applying  heat  ex- 
ternally, and  stirred  about  with  a  hot  iron  wire  till  the  inside  of 
the  bottle  becomes  coated  with  the  semi-fluid  oxide,  which  is  then 

What  are  the  sensible  properties  of  phosphorus  ? 
At  what  temperature  does'it  melt  ?     At  what  point  does  it  evaporate  ? 
By  v/hat  mechanical  means  may  phosphorus  be  ignited  ? 
What  is  the  name  given  to  the  combination  of  phosphorus  with  oxygen 
in  the  lowest  proportion  ? 

To  what  useful  purpose  may  this  compound  be  applied  ? 
What  effect  is  observed  on  placing  phosphorus  in  a  vacuum  ? 

*  It  appears  from  the  experiments  of  Dr.  John  Davy  and  others,  that 
"when  oxygen  gas  is  rarifiedjj>hospho.rus  shines  in  it:  and  that  when 
condensed  it  ceases  to  shine.  With  an  augmented  pressure  of  a  column 
of  mercury  of  16  inches,  when  heated  with  a  spirit-lamp  in  this  gas,  it 
emitted  no  light  till  it  fused  ;  then  it  burst  into  flame  and  burnt  explosive- 
ly, and  the  oxygen  was  condensed  in  an  instant Compression  and 

rarefaction,  in  the  instance  of  common  air,  has  an  effect  analogous  to  that 

mentioned  when  speaking  of  oxygen When   phosphorus    is  placed 

on  the  plate  of  an  air-pump,  under  a  receiver,  and  the  air  exhausted,  the 
brightness  of  its  light  in  the  dark  rather  increases  with  the  exhaustion  ; 
and  in  the  nearly  perfect  vacuum  formed  by  a  good  pump,  its  light  was 
not  diminished.  When  the  air  has  been  suddenly  readmitted,  the  light  has 
been  extinguished,  and  for  a  few  seconds  it  has  ceased  to  shine." — Obser- 
vations on  Phosphorus.  By  J.  Davy,  M.  D-,  F.  R.  S.,  in  Jameson's  Journal 
of  Science. 


PHOSPHORIC  ACID.  121 

to  be  preserved  for  use,  by  closing  the  bottle  with  a  cork.  When 
a  light  is  wanted,  it  is  only  necessary  to  dip  into  the  bottle  a 
brimstone-match,  and  on  withdrawing  it  with  a  small  portion  of 
the  oxide  of  phosphorus  adhering  to  its  extremity,  the  sulphur  will 
become  inflamed,  and  the  match  may  be  used  for  lighting  a  taper 
or  for  any  other  purpose. 

315.  There  is  some  uncertainty  as  to  the  number  of  the  acid 
combinations  of  phosphorus  and  oxygen.      Three  may  be  discri- 
minated as  containing  different  proportions  of  their  constituent 
elements.    These  are  the  hypophosphorous,  the  phosphorous,  and 
the  phosphoric  acids.     The  relative  quantities  of  phosphorus  and 
oxygen  in  these  acids  are  thus  stated  by  Mitscherlich  : 

Phosphoric  acid  =  100  Phosphorus  +  127.450  Oxygen. 

Phosphorous  acid          =  100  Phosphorus-}-    76.470  Oxygen. 
Hypophosphorous  acid  =  100  Phosphorus  -j-    25.490  Oxygen.* 

316.  The  phosphorous  acid  is  a  white,  volatile  substance,  which 
may  be  obtained  by  burning  phosphorus  in  a  tube,  with  a  relatively 
small  portion  of  air,  and  at  a  moderate  temperature  ;  it  may  then 
be  collected  in  the  state  of  a  white  powder,  which,  on  exposure 
to  the,  atmosphere,  decomposes  the  water  suspended  in   it,  con- 
siderable heat  is  given  out,  and  it  combines  with  an  additional 
portion  of  oxygen  to  constitute  phosphoric  acid.  The  phosphorous 
acid  speedily  dissolves  in  water,  to  which  it  gives  a  sour  taste, 
and  the  solution  reddens  vegetable  blues.    With  various  salifiable 
bases  this   acid  forms  certain  salts  called  phosphites.     Both  the 
phosphorous  and  the  phosphoric  acids  combine  in  definite  propor- 
tions with  water,  forming  hydrated  acids. 

317.  When  phosphorus  is  rapidly  inflamed,  as  in  its  combus- 
tion in  oxygen  gas,  abundance  of  white  vapours  are  produced, 
which  become  condensed  into  deliquescent  flakes,  adhering  to  the 
interior  of  the  receiver,  or  falling  to  the  bottom  like  snow ;  this 
substance  is  the  phosphoric  add.     This  acid  may  also  be  obtained 
from  the  decomposition  of  atmospheric  air  by  phosphorus.     Thus 
if  a  piece  of  phosphorus  be  placed  in  a  watch-glass,  upon  a  plate 
of  glass,  and  covered  with  a  tall  receiver,  on  setting  it  on  fire  with 
a  red-hot  iron  it  will  at  first  burn  rapidly,  and  then  more  slowly 
till  the  oxygen  is  nearly  consumed.      The  combustion,  however, 
may  be  renewed  by  occasionally  lifting  the  receiver  slightly,  so  as 
to  introduce  fresh  supplies  of  air  from  time  to  time,  till  the  phos- 

How  many  acid  compounds  of  phosphorus  and  oxygen  are  known  to 
exist? 

What  are  the  relative  proportions  of  the  two  ingredients  in  each? 
What  are  the  leading  properties  of  phosphorous  acid  ? 
In  what  manner  is  phosphoric  acid  formed  ? 
How  is  it  obtained  in  an  anhydrous  state  ? 

*  Introduction  to  Chemistry,  vol.  i.  p.  389. 
L 


122  CHEMISTRY. 

phorus  is  all  burnt,  and  thus  will  be  formed  a  quantity  of  anhy- 
drous phosphoric  acid,  as  before,  in  the  form  of  flakes  of  snow. 

318.  This  substance  dissolves  in  water  with  a  hissing  noise,  and 
the  evolution  of  much  heat;  and  it  is  also  soluble  in  alcohol. 
Phosphoric  acid  may  likewise  be  obtained  by  heating  small  frag- 
ments of  phosphorus  in  nitric  acid.  Though  phosphoric  acid  will 
unite  readily  with  water,  on  heating  the  solution  the  greater  part 
of  the  water  may  be  driven  off,  and  if  the  residue  be  exposed  to  a 
low  red  heat  it  melts,  and  on  cooling  forms  a  kind  of  glass,  some- 
times called  glacial  phosphoric  acid.  The  solid  acid  attracts 
water  from  the  air;  it  has  no  smell,  but  an  intensely  sour  taste, 
and  becomes  volatilized  without  decomposition  at  a  bright  red 
heat.  It  unites  with  salifiable  bases  to  produce  the  salts  called 
phosphates,  one  of  which,  the  phosphate  of  soda,  is  used  in 
medicine  ;  and  phosphate  of  lime,  or  the  combination  of  this  acid 
with  calcareous  earth,  constitutes  a  considerable  part  of  the  bones 
of  animals,  from  the  decomposition  of  which,  as  already  stated, 
phosphorus  is  usually  obtained. 

319.  The  hypophusphorous  acid,  is  so  named   as  containing   a 
smaller  proportion  of  oxygen  than  the  phosphorous  acid.  The  salts 
formed    by  this  acid  are  all  readily  soluble,  and  highly  deliques- 
cent when  exposed  to  the  air. 

320.  The  phosphoric  acid  is  capable  of  undergoing  modifica- 
tions, which  materially  influence  its  properties,  without  causing 
any  alteration  of  the  proportions  of  its  constituents.     "  If  liquid 
phosphoric  acid  be  exaporated,  and  heated  to  such  a  temperature 
as  may  be  judged  capable  of  expelling  the  chief  part  of  the  water, 
it  is  changed  into  pyrophosphoric  acid :    and  the  same  change 
takes  place  when  the  acid  exists  in  a  salt  combined  with  an  alkali. 
Although  between  phosphoric  and  pyrophosphoric  acid  there  is 
no  known  difference  of  composition,  the  properties  of  each  are 
essentially  different.      Pyrophosphoric  acid  produces,  with  oxide 
of  silver,  a  white  salt ;  phosphoric  acid,  a  yellow  one  :  the  former 
is  a  less  energetic  acid,  it  has  less  saturating  power,  and  is  even 
separated  from  its  combinations  by  phosphoric  acid."* 

321.  This  apparent  identity  of  composition  occurs  in  various 
other  compounds,  constituting  the  phenomenon  which  has  been 


How  is  phosphoric  acid  obtained  in  a  glacial  state? 

What  are  ihe  chief  properties  of  this  acid  ? 

In  what  form  of  combination  does  phosphorus  exist  in  animals? 

What  changes  may  phosphoric  acid  undergo  without  changing  the  pro- 
portions of  its  constituents  ? 

What  striking  difference  exists  between  phosphoric  and  pyrophosphoric 
acid  t 


*  Donovan's  Treatise  on  Chemistry,  in  Cabinet  Cyclopaedia,  p.  221.  See 
also  Mitscherlich's  Introduction  to  Chemistry,  vol.  i.  pp.  391 — 394  ;  and 
Johnston  on  Chemistry,  in  Report  of  British  Association  for  1832,  pp.  457 — 


PROTOCHLORIDE  OF  PHOSPHORUS.  123 

termed  Isomerism.*  Another  instance  of  it  will  be  found  in  the 
combination  of  phosphorus  with  hydrogen,  in  the  existence  of  two 
oxides  and  two  chlorides  of  tin,  differing  in  properties,  but  having 
the  same  atomic  constitution,  in  some  other  combinations  of  oxy- 
gen with  metals,  and  in  some  of  the  acids  with  compound  radicals. 
Among  the  numerous  carburets  of  hydrogen,  cases  of  a  corre- 
sponding mode  of  union  have  been  noticed,  giving  rise  to  what  is 
termed  Polymerism;*  and  there  is  another  kind  of  relation  be- 
tween the  combining  proportions  of  bodies  expressed  by  the  term 
Metamerism.*  These  phenomena  have  so  much  similitude,  that 
their  origin  may  with  probability  be  referred  to  a  common  cause  ; 
but  the  subject,  which  is  highly  interesting,  requires  further  in- 
vestigation. 

322.  Phosphorus  combines  with  chlorine  in  two  proportions. 
Protochloride  of  phosphorus  may  be  obtained  by  distilling  phos- 
phorus mixed  with  corrosive  sublimate,  or  perchloride  of  mercury, 
when  calomel,  or  protochloride  of  mercury  will  be  formed  by  the 
decomposition  of  the  sublimate,  and  the  portion  of  its  chlorine, 
which  is  thus  set  free,  will  immediately  combine  with  the  phos- 
phorus. Protochloride  of  phosphorus  when  first  obtained,  is  a 
liquid  of  a  reddish  colour,  holding  some  phosphorus  in  solution, 
which  it  deposits  on  standing.  It  then  becomes  transparent  and 
colourless.  Its  specific  gravity  is  1.45.  It  has  a  suffocating  smell, 
and  gives  off  acid  fumes  when  exposed  to  the  air,  owing  to  its 
absorbing  wrater,  which  it  readily  decomposes,  the  hydrogen  of  the 
water  combining  with  chlorine  to  form  muriatic  acid,  and  the  oxy- 
gen with  the  phosphorus  to  form  phosphorous  acid.  Its  vapour  is 
combustible  ;  and  when  in  a  dry  state,  it  does  not  affect  the  colour 
of  vegetable  blues. 

To  what  phenomenon  is  the  term  Isomerism  applied  ? 

What  is  meant  by  Polymerism  ?  —  Metamerism  ? 

What  two  compounds  are  formed  by  phosphorus  and  chlorine? 

Describe  the  process  of  obtaining  the  prolochloride  of  phosphorus? 

What  are  its  properties  ? 


*  Isomerism  is  a  term  derived  from  the  Greek  "Iffoj,  equal,  and 
a  part  ;  Polymerism  from  IIoXvs,  many,  and  Mepoj;  and  Metamerism  from 
Mer/l,  according  to,  and  Mcpoj.  The  following  explanation  of  these  terms 
is  given  by  Mr.  Johnston:  "  Isomeric  bodies  are  those  which  contain  the 
same  absolute  and  relative  number  of  atoms  of  the  same  elements,  and 
have  consequently  the  same  atomic  weight.  Polymeric  are  those  which 
contain  the  same  relative,  but  not  the  same  absolute  number  of  atoms  of 
the  same  elements,  and  whose  atomic  weights  are  consequently  unlike. 
Metameric  are  those  which,  while  ihey  contain  the  same  absolute  and  the 
same  relative  number  of  atoms  of  the  same  elements,  yet  constitute  sub- 
stances belonging  to  an  entirely  different  class  of  bodies,  or  a  different  or- 
der of  chemical  compounds."  —  Reports  of  the  British  Association  for  1832, 
pp.  435,  436. 

Isomorphism,  (from  the  Greek  "I«n>y,  and  Mop<£jj,  figure,  or  shape,)  corre- 
spondence of  form  between  bodies  composed  of  different  elements,  refers 
to  another  class  of  chemical  phenomena,  brought  to  light  through  the  re- 
searches of  men  science.  It  occurs  in  crystalline  bodies,  nnd  will  be  fur- 
ther noticed  in  the  Treatise  on  Mineralogy, 


124 


CHEMISTRY. 


323.  Perchloride  of  phosphorus. — When  phosphorus  is   intro- 
duced into  chlorine  gas,  it  takes  fire  spontaneously,  burning  with 
a  pale  flame,  and  the  product  is  a  white  pulverulent  substance, 
which  condenses  on  the  sides  of  the  vessel.     It  is  volatile  at 
temperatures  under  212°,  but  if  heated  under  pressure,  it  fuses 
and  becomes  crystallized  on  cooling.      It  acts  violently  on  water, 
double  decomposition  taking  place,  and  hydrochloric  or  muriatic 
acid,  and  phosphoric  acid  being  produced. 

324.  Phosphorus  very  readily  combines  with  iodine,  for  when 
these  substances  are  mixed  in  an  exhausted  vessel,  great  heat  is 
evolved  but  no  light,  and  the  result  is  a  reddish  or  orange-coloured 
compound,  the  iodide  of  phosphorus,  which  powerfully  decomposes 
water.     Periodide  of  phosphorus  is  a  black  compound,  which  may 
be  formed   by  heating  together  its  constituent  parts,  and  like  the 
preceding  it  decomposes  water. 

325.  According  to  M.  Balard,  phosphorous  combines  with  bro- 
mine in  two  proportions,  but  the  compounds  thus  formed  have 
been  but  slightly  examined. 

326.  Phosphorus  combines  with  hydrogen  to  form  two  com- 
pounds.    The  former  of  these,  called  phosphuretted  hydrogen,  may 
be  readily  procured  by  heating  phosphorus  in  a  solution  of  caustic 
potash. 


327.  This  combination  may  be  formed  by  means  of  the  apparatus 
represented  in  the  preceding  figure.  Let  about  a  quarter  of  an 
ounce  of  phosphorus  be  introduced  into  the  small  retort,  A,  which 
is  to  be  rilled  up  to  its  neck  with  the  solution  of  caustic  potash, 
and  the  lower  end  of  the  retort  is  to  be  dipped  under  water  in  the 
trough  B  ;  then,  on  heating  the  retort  gradually  with  a  lamp,  gas 
will  be  generated,  which  will  rise  from  the  end  of  the  tube,  through 
the  water,  in  bubbles,  and  these  on  coming  in  contact  with  the  air 
will  inflame  with  a  slight  explosion.  When  the  atmosphere  is 
still,  each  bubble  as  it  bursts  produces  an  expanding  ring  of  dense 
vapour,  resulting  from  the  sudden  formation  of  phosphoric  acid  and 
water.  Some  care  is  necessary  in  the  conduct  of  this  experiment, 
so  as  to  include  as  small  a  portion  of  air  as  possible  in  the  retort, 

How  is  perchloride  of  phosphorus  procured  ? 
How  many  and  what  compounds  does  it  form  with  iodine  ? 
How  many  compounds  does  it  make  with  hydrogen  ? 
How  is  phosphuretted  hydrogen  obtained  ? 

What  peculiar  phenomenon  attends  the  rising  of  bubbles  of  this  gas  into 
the  open  air  ? 


PHOSPHURET  OF  CARBON.  125 

since  the  first  bubbles  of  phosphuretted  hydrogen  gas  that  are 
formed  will,  as  soon  as  they  come  in  contact  with  the  air  in  the 
retort,  take  fire,  and  the  retort  may  be  broken  by  the  percussion. 

3-28.  This  gas  may  also  be  procured  by  dropping  small  pieces 
of  the  compound  called  phosphuret  of  lime,  into  muriatic  acid, 
largely  diluted  with  water,  and  the  gas  rising  as  before,  will  take 
fire  on  coming  in  contact  with  the  air.  The  same  compound  may  be 
obtained  by  heating  in  close  vessels  solid  hydrated  phosphoric  acid  ; 
and  the  gas  produced  by  this  or  either  of  the  preceding  operations, 
may  be  preserved  by  suffering  it  to  pass  into  an  inverted  jar  filled 
with  water,  when  it  will  rise  to  the  top,  and  gradually  displace 
that  liquid.  Phosphuretted  hydrogen  is  a  colourless  gas,  with 
a  nauseous  smell,  like  onions  or  asafoetida,  and  a  very  bitter  taste. 
It  loses  its  inflammable  property  by  being  kept  over  water,  which 
absorbs  about  two  per  cent,  of  the  gas,  and  thus  acquires  its  cha- 
racteristic taste  and  odour.  It  burns  with  great  splendour  in  oxy- 
gen gas,  in  chlorine  with  a  beautiful  pale  blue  light,  and  it  also 
burns  in  nitrous  oxide. 

329.  The  gas  which  has  been  styled  lihydmguret  of  phosphc/rus^ 
or  hydrophosphoric  gas.  may  be  obtained  by  heating  the  solid 
hydrated  phosphoric  acid,  in  a  small  retort,  and  collecting  the  pro- 
duct over  mercury.    It  is  colourless,  and  resembles  the  preceding 
compound  in  taste  and  smell,  but  is  less  disagreeable.     Though 
it  does  not  inflame  spontaneously  in  atmospheric  air,  it  explodes 
when  heated  to  300°,  and  more  readily  when  heated  in  oxygen 
gas ;   it   also   takes   fire  spontaneously  in   chlorine.      Professor 
Henry  Rose  has  ascertained  that  this  and  the  preceding  are  iso- 
meric  bodies ;    so  that  there  are  two  kinds  of  phosphuretted  hy- 
drogen, one  which  inflames  spontaneously  in  atmospheric  air,  and 
another  which  is  relatively  non-inflammable,  both  consisting  of  one 
volume  of  phosphorus  in  vapour,  and  three  volumes  of  hydrogen 
gas,  condensed  to  the  bulk  of  two  volumes. 

330.  The   combination   of  phosphorus  with  carbon   was  first 
effected  by  M.   Proust.     Phosphuret  of  carbon  may  be  obtained 
from  phosphuret  of  lime,  by  suffering  it  to  remain  in  water  till  it 
gives  out  no  more  gas ;  a  considerable  excess  of  muriatic  acid  is 
then  to  be  added  to  the  liquid,  and  after  agitating  it  a  few  moments 
it  must  be  thrown  on  a  filter,  and  the  substance  which  remains  on 
it  is  to  be  washed  and  dried.     It  seems  from  this  process  that 
carbon  is  contained  in  phosphuret  of  lime,  as  usually  prepared, 
and   it   is  also  procured  in  the  process  for  making  phosphorus. 
Phosphuret  of  carbon  is  a  soft  powder,  of  a  dull  lemon  colour, 
destitute  of  taste  or  smell,  which  when  exposed  to  air  absorbs 

How  is  the  phosphuretted  hydrogen  obtained  from  phosphuret  of  lime? 
How  is  the  inflammability  of  this  gas  destroyed? 
How  is  hydrophosphoric  acid  procured  ? 
What  are  its  sensible  properties? 
What  chemical  characteristics  does  it  present? 

What  is  the  proportion  of  phosphorus  and  hydrogen  in  their  two  isomeric 
compounds  ?     What  ia  the  process  for  procuring  phosphuret  of  carbon? 
L2 


126  CHEMISTRY. 

water,  which  it  decomposes,  becoming  converted  into  phosphorus 
acid.  Exposed  to  a  red  heat  it  burns,  and  gradually  gives  out  its 
phosphorus,  the  charcoal  remaining  behind  in  the  form  of  a  black 
substance,  coated  with  phosphoric  acid,  which  prevents  its  com- 
plete combustion.  When  the  powdered  phosphuret  is  thrown  over 
the  fire  in  small  quantities,  it  forms  beautiful  scintillations. 

-T* 

Sulphur. 

331.  This  substance  is  well  known,  as  being  of  common  oc- 
currence, and  employed  in  medicine  and  the  arts  for  a  variety  of 
purposes.     It  is  often  found   in   volcanic   districts,   among  the 
matter  discharged  from  the  craters  of  burning  mountains,  and  in 
several  states  of  combination  it  forms  a  constituent  of  numerous 
minerals.   Flowers  of  sulphur  and  roll  sulphur  differ  only  as  to  their 
state  of  aggregation.   The  latter  exhibits  a  crystalline  structure, 
especially  if  melted,  and  suffered  to  cool  slowly.   Though  sulphur 
may  be  considered  as  an  insipid  and  almost  inodorous  body,  it  ex- 
hales a  peculiar  smell  when  heated  or  exposed  to  friction.  Heat  and 
friction  also  render  it  highly  electric,  and,  like  sealing-wax,  it  is  a 
non-conductor  of  electricity.     When  raised  to  the  temperature  of 
about  180°  Fahrenheit,  it  sublimes,  strongly  exhibiting  its  charac- 
teristic odour ;  at  about  220°  it  becomes  fused,  and  if  the  heat  is 
increased  and  continued,  it  forms  a  viscid  semi-solid  mass,  which, 
when  poured  into  warm  water,  assumes  the  consistency  of  soft 
wax,  exhibiting  a  red  tint ;  and  in  this  plastic  state,  it  is  used  for 
taking  impressions  of  coins,  medals,  or  sculptured  gems,  as  it 
becomes  quite  hard  on  cooling.    Sublimed  sulphur,  (flowers  of 
sulphur,)  when  examined  by  a  microscope,  is  found  to  consist  of 
minute  crystals. 

332.  Sulphur  is  well  known  to  be  highly  inflammable,  com- 
bining with  the  oxygen  of  atmospheric  air,  even  at  the  tempera- 
ture of  190°;  though  it  then  burns  but  slowly,  with  a  faint  blue 
light;  but  at   300°    its   combustion  goes  on  rapidly,   with  the 
evolution  of  much  light  and  heat.   In  oxygen  gas  it  burns  brightly, 
producing  a  large  lilac-tinted  flame.     It  combines  with  oxygen  in 
four  different  proportions,  to  form  definite  compounds,  all  of  which 
are  acids,  whose  relative  composition  will  appear  from  the  follow- 
ing table : 

Sulphuric  acid  =  100  Sulphur  -j-  149.136  Oxygen. 

Hyposulphuric  acid  =  100  Sulphur  -f  124.280  Oxygen. 
Sulphurous  acid  =  100  Sulphur  -j-  99.420  Oxygen. 
Hyposulphurus  acid  =  100  Sulphur  -j-  49.710  Oxygen. 

In  what  forms  does  sulphur  occur  in  nature  ? 

Whnt  is  the  difference  between  the  two  forms  in  which  it  is  met  with 
in  commerce  ? 

Does  this  substance  necessarily  pass  through  the  liquid  state  in  changing 
from  a  solid  to  a  vapour? 

In  how  many  proportions  does  sulphur  combine  with  oxygen? 

What  are  the  respective  products  of  these  combinations  ? 


SULPHURIC  ACID.  127 

333.  Sulphurous  acid. — This  is  a  gaseous  compound,  which  may 
be  obtained  by  the  direct  union  of  its  constituents,  when  sulphur 
is  burnt  in  atmospheric  air,  perfectly  free  from  moisture,  or  in 
oxygen  gas.     It  may  also  be  procured  by  boiling  two  parts  of 
mercury  in  three  of  sulphuric  acid  ;  or  by  heating  together,  in  a 
small  glass  retort,  equal  parts  of  powdered  black  oxide  of  manga- 
nese and  flowers  of  sulphur.    In  the  former  of  these  processes,  the 
mercury  partially  decomposes  the  sulphuric  acid,  becoming  oxi- 
dated by  uniting  with  a  portion  of  its  oxygen,  and  sulphurous 
acid  gas  is  thus  formed.     In  the  latter  case,  the  sulphur  attracts 
from  the  metallic  peroxide  a  part  of  its  oxygen,  and  the  gaseous 
acid  is  produced  as  before. 

334.  This  gas  must  be  collected  and  preserved  over  mercury, 
as  water  absorbs  more  than  thirty  times  its  volume  of  it.   It  com- 
municates to  water  the  odour  of  burning  brimstone,  and  an  astrin- 
gent acid  taste.     At  first  the  solution  bleaches  vegetable  colours, 
but  after  being  kept  some  time,  it  changes  blue  colours  to  red. 
The  gas  equally  effaces  colours,  and  it  is  therefore  used  in  bleach- 
ing silk,  cotton,  straw,  and  other  substances.    It  has  likewise  the 
property  of  checking  vinous  fermentation,  and  it  is  hence  occasion- 
ally employed  in  the  processes  of  brewing  and  mixing  wines.  This 
gas  is  not  inflammable,  extinguishing  burning  bodies  which  are 
plunged  into  it;  hence  when  the  soot  is  on  fire  in  a  foul  chimney, 
if  it  be  filled  with  the  fumes  of  sulphurous  acid,  by  heating  sul- 
phur below  on  an  iron  plate,  the  fire  will  be  put  out,  as  the  soot 
cannot  burn  in  an  atmosphere  of  this  gas.     It  is  speedily  destruc- 
tive to  animals  confined  in  it. 

335.  Sulphurous  acid  may  be  condensed  to  the  liquid  state,  by 
exposure  to  pressure  equal  to  the  weight  of  two  atmospheres,  -at 
the  temperature  of  45°,  and  by  means  of  intense  cold,  independent 
of  pressure.     In  this  form  the  specific  gravity  has  been  estimated 
at  1.45,  and  it  boils  at  14°,  inducing  the  speedy  congelation  of 
liquids  in  contact  with  it  by  its  rapid  evaporation. 

336.  Sulphuric  acid. — The  quantity  of  oxygen  contained  in  this 
acid  is  just  half  as  much  again  as  that  in  the  preceding  compound, 
and  therefore  sulphuric  acid  may  be  produced  by  combining  sul- 
phurous acid  with  an   additional  portion  of  oxygen.     The  acid 
gas  will  not  unite  with  oxygen  when  simply  mixed  with  it,  with- 
out the  intervention  of  some  other  body ;  but  if  water  be  present 
the  combination  may  be   effected.     Thus  when   oxygen  gas  is 
inclosed  in  an  inverted  jar  over  an  aqueous  solution  of  sulphurous 
acid  the  oxygen  will  be  slowly  absorbed,  and  sulphuric  acid  may 
be  thus  obtained,  largely  diluted  with  water,  a  considerable  por- 
tion of  which  may  be  expelled  by  evaporation. 

337.  This  acid  is  used  for  numerous  purposes,  and  is  there- 
How  is  sulphurous  acid  obtained  ? 

What  chemical  effects  does  it  produce  ? 

How  is  the  extinction  of  fire  in  chimneys  by  throwing  sulphur  into  the 
fire  to  be  accounted  for  ? 
In  how  many  ways  may  sulphurous  acid  be  condensed  into  a  liquid  ? 


128  CHEMISTRY. 

fore  manufactured  on  an  extensive  scale,  the  process  generally 
adopted  being  founded  on  the  same  principle  with  that  just 
described.  It  consists  essentially  in  burning  a  mixture  of  about 
eight  parts  of  sulphur  and  one  of  nitre,  (nitrate  of  potash,)  in  a 
close  chamber  lined  with  lead,  and  containing  water.  Here  sul- 
phurous acid  is  first  formed  from  the  combustion  of  the  sulphur, 
and  the  partial  decomposition  of  the  nitrate  of  potash  furnishes 
the  additional  quantity  of  oxygen,  to  form  sulphuric  acid,  when 
the  products  of  the  combustion  come  in  contact  with  the  water. 
The  acid  thus  procured  is  afterwards  concentrated  by  boiling,  and 
purified  by  distillation. 

338.  Another  method  of  obtaining  this  acid  is  from  the  decom- 
position of  sulphate  of  iron,  or  the  compound  of  sulphuric 
acid  and  oxide  of  iron,  when  distilled  from  earthen  retorts  in  a 
reverberatory  furnace.  The  salt  used  in  this  operation  being 
called  green  vitriol,  or  martial  vitriol,  the  acid  which  it  produced 
received  the  name  of  oil  of  vitriol,  with  reference  to  its  consist- 
ence and  general  appearance.  This  acid  emits  whitish  or  gray 
vapours  when  exposed  to  the  air,  and  if  it  be  distilled  with  a  gentle 
heat,  and  the  receiver  kept  cool  with  snow  or  pounded  ice,  a 
transparent  colourless  vapour  will  pass  over,  and  become  con- 
densed into  a  crystalline  solid,  resembling  fibres  of  asbestos, 
which  is  the  pure  acid. 

331).  The  anhydrous  acid,  thus  prepared,  is  so  extremely  vola- 
tile, that  it  rises  in  fumes  at  a  low  temperature,  and  greedily 
attracts  moisture  from  the  air.  Liquid  sulphuric  acid  consists  of 
81.63  parts  by  weight  of  the  pure  or  anhydrous  acid,  and  18.37  of 
water.  It  then  forms  the  oily  fluid  already  described,  which  has 
the  specific  gravity  of  1.85,  which  boils  at  600°,  and  freezes  at 
15°,  undergoing  in  the  solid  state  a  considerable  amount  of  con- 
traction. It  readily  absorbs  moisture  from  the  air,  whence  its 
application  in  many  processes  for  the  purpose  of  obtaining  gases 
free  from  aqueous  vapour.  When  mingled  with  a  moderate 
quantity  of  water,  it  produces  a  high  degree  of  heat.  The  con- 
centrated acid  acts  as  a  caustic  when  applied  to  the  skin,  and  it 
blackens  and  corrodes  both  animal  and  vegetable  substances. 
According  to  Dr.  Ure,  the  solid  or  anhydrous  sulphuric  acid,  if 
dropped  on  paper,  will  burn  holes  in  it  as  readily  as  a  red-hot 
iron,  and  when  dropped  into  water  it  hisses  as  if  a  red-hot  coal 
had  been  thrown  into  it :  at  the  temperature  of  64°  it  dissolves 
into  a  thin  liquid. 

340.  Hyposulphurous  acid  may  be  formed  by  digesting  filings 
of  iron  in  water  impregnated  with  sulphurous  acid  gas,  which  is 
partially  decomposed,  forming  oxygen  and  hyposulphurous  acid ; 
the  oxygen  combines  with  the  metal  to  form  oxide  of  iron,  which 

In  what  manner  may  sulphurous  be  converted  into  sidphiific  acid  ? 
How  is  this  acid  manufactured  for  the  purposes  of  the  arts? 
How  is  the  pure  acid  obtained  ? 

What  are  the  properties  of  the  anhydrous  sulphuric  acid  ? 
How  may  the  hyposulphurous  acid  be  formed  ? 


HYDROSULPHURIC  ACID.  129 

unites  with  the  acid,  and  the  result  is  the  salt  called  hyposul- 
phite of  iron,  remaining  in  solution  in  the  water.  Various  com- 
pounds of  this  acid  with  bases  may  be  obtained  by  other  processes ; 
but  it  seems  questionable  whether  it  can  be  procured  in  an  un- 
combined  state.  Dr.  Thomson  announced  the  production  of  an 
acid  of  sulphur  containing  a  larger  proportion  of  oxygen  than 
the  preceding,  but  less  than  any  of  the  others,  (its  combining 
quantity  of  oxygen  being  a  mean  between  the  hyposulphurous 
and  the  sulphurous  acids,)  to  which  he  gave  the  appellation  of 
subsulphurous  acid.  But  from  an  analysis  of  hyposulphite  of 
barytes,  and  other  experiments  of  Professor  Rose,  it  appears  that 
this  acid  consists  of  the  same  constituents  as  the  hyposulphurous, 
and  in  the  same  proportions,  but  each  atom  contains  double  the 
number  of  atoms  of  sulphur  and  of  oxygen.  It  is,  therefore,  an 
example  of  a  polymeric  compound. 

341.  Hyposulphuric  add. — When  sulphurous  acid  gas  is  passed 
through  water  in  which  the  powder  of  black  oxide  of  manganese  is 
kept  suspended  by  agitation,  the  metallic  oxide  becomes  partly  de- 
composed, and  the  oxygen  which  it  gives  out  combines  with  the 
sulphurous  acid  in  two  proportions,  forming  sulphuric  and  hypo- 
sulphuric  acid.     Both  these  acids  will  unite  with  the  oxide  of 
manganese,  and  to  obtain  the  hyposulphuric  separate,  solution  of 
barytes  must  be  added,  which  will  decompose  the  metallic  salts, 
forming  a  soluble  hyposulphate,  while  the  other  ingredients  will 
be  precipitated.     The  hyposulphate  of  barytes  is  then  to  be  de- 
composed by  means  of  sulphuric  acid,  and  the  hyposulphuric  acid 
thus  obtained  may  be  concentrated  by  placing  it  under  the  ex- 
hausted receiver  of  an  air-pump,  with  sulphuric  acid.     The  acid 
which  may  thus  be  raided  to  the  specific  gravity  of  1.347,  is  an 
inodorous  liquid  which  reddens  litmus  paper.     It  forms  soluble 
salts  not  only  with  barytes,  but  likewise  with  lime,  strontia,  and 
protoxide  of  lead ;  thus  essentially  differing  from  the  sulphuric 
acid. 

342.  Sulphur  does  not  apparently  combine  with  nitrogen,  but 
with  hydrogen  it  forms  two  compounds,  both  which,  like  acids, 
unite  with  the  alkaline  and   other  bases  to  form  a  kind  of  salts. 
That  which  contains  the  smaller  proportion  of  sulphur,  has  been 
called  sulphuretted  hydrogen,  and  sometimes   hydrosulphuric,   or 
hydrothionic*  acid.     It  may  be  formed  indirectly  by  pouring  sul- 
phuric acid,  diluted,  on  combinations  of  iron  or  other  metals  with 
sulphur.     It  is  a  colourless  transparent  gas,  readily  absorbed  by 
water,  and  has  a  very  offensive  smell,  similar  to  that  observable 
in  putrid  eggs,  or  in  the  washings  of  a  foul  gun-barrel  j  the  peculiar 

Plow  the  hvposulphuric  ? 

What  are  the  chemical  properties  of  this  acid  which  distinguish  it  from 
the  sulphuric  ? 

How  many  compounds  are  produced  between  hydrogen  and  sulphur  ? 

How  is  hydrosulphuric  acid  obtained  ? 

What  are  its  sensible  and  what  its  chemical  properties  ? 

*  From  the  Greek  "YJwp,  water,  and  QeTov,  sulphur. 


130 


CHEMISTRY. 


odour  in  these  and  other  cases  of  its  occurence,  depending  on  the 
presence  of  this  gas.  Hydrosulphuric  acid  appears  to  be  com- 
posed of  100  parts  by  weight  of  sulphur,  and  6.184  of  hydrogen. 
It  reddens  litmus  paper,  and  combines  with  many  of  the  salifiable 
bases,  forming  a  class  of  salts  called  hydrosulphates,  which  are 
decomposed  by  all  the  oxygen  acids  except  the  carbonic. 

343.  Hydrosulphuric  acid  gas  is  inflammable,  burning  when 
mixed  with  common  air  or  oxygen,  but  it  extinguishes  other  burn- 
ing bodies  immersed  in  it.      It  tarnishes  quicksilver,  gold,  and 
mercury,  and  blackens  white  oxide  of  lead,  (ceruse,)  or  that  of 
bismuth. 

One  of  the  modes  in  which  this  pro- 
perty of  reducing  the  oxides  of  metal  pos- 
sessed by  hydrosulphuric  acid  may  be  ex- 
hibited, is  shown  in  the  annexed  figure. 
The  figure  is  to  be  drawn  on  a  large  scale 
in  acetate  of  lead,  which,  until  acted  on 
by  the  acid,  will  remain  colourless,  but 
when  a  stream  of  the  gas,  also  invisible, 
is  allowed  to  fall  upon  the  still  moist  sur- 
face, the  lines  traced  instantly  become 
black.  The  oxide  of  lead,  one  of  the  in- 
gredients of  the  acetate  of  lead,  yields  its 
oxygen  to  the  hydrogen  of  the  hydrosul- 
phuric acid,  while  the  lead  itself  combines  with  the  sulphur  of  the 
gas  to  form  sulphuret  of  lead,  the  black  colour  of  which  constitutes 
the  visible  lines  of  the  picture.* 

344.  It  is  highly  noxious  to  animal  life  when  respired,  and  it 
has  been  said  that  a  horse  has  been  known  to  perish  in  air  con- 
taining only  ~-Q  part  of  this  gas.     It  is,  however,  sometimes  em- 
ployed medicinally,  when  largely  combined  with  water,  being 
used  in  this  state  for  bathing,  and  taken  internally.  Many  mineral 
springs  derive  their  sensible  qualities  from  the  hydrosulphuric 
gas  with  which  they  are  impregnated. 

345.  Bisulphnret  of  hydrogen,  or  super-sulphuretted  hydrogen, 
called   also  hydrosulphuroiis  ac/W,  is    a  compound    containing  a 
larger  portion  of  sulphur  than  the  former.     It  is  a  yellow,  oily 
liquid,  heavier  than  water,  greatly  resembling  in  its  smell  and 
taste  the  solution  of  sulphuretted  hydrogen. 

346.  Sulphur  unites  with  chlorine  to  form  a  volatile   liquid, 
which  exhibits  a  red  colour  when  viewed  by  reflected  light,  and  a 
greenish-yellow  tint  by  transmitted  light.    This  compound  called 

What  are  the  proportions  of  its  ingredients  ? 
How  may  its  action  on  a  salt  of  lead  be  produced  ? 
Describe  the  sympathetic  picture. 
What  are  the  effects  of  this  acid  on  animal  life  ? 
In  what  natural  situations  does  this  gas  occur  ? 


*  The  figure  has  been  derived  from  Dr.  Hare,  who,  in  his  Compendium, 
calls  it  the  sympathetic  picture. 


SULPHURET  OF   CARBON.  131 

chloride  of  sulphur  may  be  formed  by  passing  a  current  of  chlorine 
through  flowers  of  sulphur,  or  by  heating  the  latter  in  dry  chlorine 
gas.  It  has  a  strong  peculiar  smell,  and  a  hot  acid  taste  ;  but  it 
does  not  affect  vegetable  blue  colours  unless  water  be  present, 
which  decomposes  it.  It  is  also  decomposed  by  many  other  sub- 
stances ;  but  it  readily  dissolves  sulphur  and  phosphorus,  and 
holds  them  in  solution.  It  decomposes  ammonia,  and  likewise 
alcohol  and  ether,  and  is  decomposed  by  mercury,  heat  being 
given  out,  sulphur  deposited,  and  chloride  of  mercury  formed. 

347.  Sulphur  combines  with  iodine  when  they  are  exposed  to- 
gether to  a  gentle  heat,  and  the  product  is  a  black  crystallizable 
substance  named  iodide  of  sulphur.     It  becomes  decomposed  by  a 
degree  of  heat  not  much  beyond  that  required  for  its  formation, 
the  iodine  in  this  case  being  driven  off  in  the  form  of  vapour. 

348.  Bromide  of  sulphur  is  produced  when  bromine  and  sulphur 
are  digested  together.  This  compound  is  a  red  liquid,  fuming  when 
exposed  to  air,  which  scarcely  acts  on  paper  tinged  with  litmus, 
unless  moisture  be  present,  when  it  changes  the  blue  colour  to 
red.     It  acts  violently  on  water  at  the  boiling  point,  sulphuretted 
hydrogen  being  given  out,  and  hydrobropiic  and  sulphuric  acids 
formed. 

349.  Sulphuret  of  carbon  may  be  obtained  by  passing  the  vapour 
of  sulphur  through  a  porcelain  tube,  containing  small  pieces  of 
charcoal,  quite  free  from  moisture,  and  made  red-hot,  placing  the 
tube  somewhat  inclined  across  a  chafing-dish,  or  by  distilling 
about  six  parts  of  yellow  iron  pyrites  (bisulphuret  of  iron)  with 
one  of  charcoal ;  and  the  product  in  either  case  may  be  suffered  to 
fall  from  the  lower  end  of  the  tube  into  a  jar  of  water,  the  tube  dip- 
ping beneath  its  surface.     The  sulphuret  of  carbon  passing  over 
in  a  state  of  vapour,  will  be  condensed  by  the  water  to  a  liquid, 
which  may  be  purified  by  redistillation,  at  a  low  temperature,  over 
chloride  of  calcium  (muriate  of  lime.)     The  compound  thus  ob- 
tained is  a  colourless,  transparent  fluid,  with  a  pungent  and  some- 
what aromatic  taste,  but  a  most  nauseous  and  fetid  smell.     It  is 
highly  volatile,  boils  at  a  temperature  of  about  106°,  and  has 
never  yet  been  congealed  by  artificial  cold.     Its  specific  gravity 
is  1.272.     From  its  extreme  volatility  it  has  been  employed  with 
advantage  to  produce  a  very  low  temperature  by  evaporation. 

350.  If  the  bulb  of  a  thermometer  be  covered  with  lint  wetted 
with  this  liquid,  the  mercury  will  sink  rapidly  from  60°  to  zero 
of  Fahrenheit ;  and  under  the  exhausted  receiver  of  an  air-pump, 
the  'temperature  may  be  reduced  even  to  80°  below  zero,  so  that 

How  is  chloride  of  sulphur  obtained  ? 

How  does  sulphur  react  with  iodine  ? 

What  are  the  properties  of  the  resulting  compound  ? 

What  are  the  properties  and  effects  of  bromide  of  sulphur? 

How  is  sulphuret  of  carbon  procured  ? 

In  what  state  is  the  sulphure*  of  carbon  obtained  ? 

What  are  its  chemical  properties  ? 

For  what  purpose  lias  it  been  employed  ? 


132  CHEMISTRY. 

mercury  may  by  this  means  be  readily  congealed.  Sulphuret  of 
carbon  is  not  soluble  in  water,  but  mixes  with  alcohol  and  ether, 
and  also  with  oils;  and  it  dissolves  sulphur,  phosphorus,  and 
camphor.  It  is  inflammable,  taking  fire  in  the  air  at  a  low  tem- 
perature, and  burning  with  a  blue  flame;  and  its  combustion  in 
oxygen  gas  produces  sulphurous  and  carbonic  acids. 

351.  Sulphuret  of  phosphorus. — Sulphur  unites  with  phosphorus, 
when  it  is  added  in  small  quantities  to  phosphorus  melted  in  water 
at  a  temperature  of  about  150°.     It  may  be  also  formed  by  fusing 
together  those  inflammable  bodies  in  an  exhausted  vessel.     The 
compound  is  a  reddish-brown  crystallizable  substance,  which  be- 
comes fluid  at  about  40°.     It  does  not  readily  decompose  water, 
but  it  is  more  inflammable  than  phosphorus,  and  may  be  used  like 
the  oxide  of  phosphorus  for  lighting  matches. 

Selenium. 

352.  This  is  a  rare  and  singular  substance,  discovered  within 
the  last  twenty  years,  by  Professor  Berzelius,  while  examining 
sulphuric  acid,  manufactured  from  pyrites  (sulphuret  of  iron)  pro- 
cured at  Fahlun,  in  Sweden.     Selenium,  like  sulphur,  is  capable 
of  subsisting  under  the  solid,  liquid,  or  gaseous  form ;  being  a 
solid  at  common  temperatures,  and  at  the  heat  of  above  100° 
becoming  liquid.     It  was  observed,  that  the  sulphuric  acid  ob- 
tained from  the  pyrites  of  Fahlun,  deposited  a  reddish  matter, 
which  in  burning  gave  out  a  particular  srnell,  and  which  consisted 
principally  of  sulphur,  having,  however,  mixed  with  it  a  very 
minute  quantity  of  selenium.      This  substance  has  been  since 
found  in  several  of  the  metallic  ores  from  the  Hartz  mines,  and 
among  some  of  the  volcanic  products  of  the  Lipari  Islands  ;  and  in 
England,  in  the  pyrites  of  the  Isle  of  Anglesey. 

353.  The  processes  for  obtaining  it  in  a  pure  state  are  laborious 
and  difficult,  when  it  is  necessary  to  separate  it  from  the  substances 
with  which  it  is  naturally  found  in  combination  ;  but  it  may  be 
most  readily  procured  by  decomposing  one  of  its  compounds  with 
oxygen  (selenic  acid.)     Selenium  in  the  state  of  powder  has  a 
deep  red  colour.  Its  particles,  when  compressed,  unite  ;  and  when 
warm  it  is  very  ductile,  and  may  be  drawn  out  into  fine  threads, 
the  colour  of  which  is  red  if  viewed  by  transmitted,  and  gray  by 
reflected  light.     It  boils  at  a  temperature  of  about  600°,  and  is 
converted  into  a  yellow  vapour,  forming,  when  condensed,  dark 
drops,  which  run  together  like  quicksilver;  and  when  heated  in 
large  vessels,  or  in  the  open  air,  it  forms  a  sublimate  like  flowers 

In  what  liquids  may  it  be  dissolved  ? 

What  are  the  products  of  its  combustion  ? 

By  what  means  may  sulphur  be  made  to  unite  with  phosphorus  ? 

When  and  by  whom  was  selenium  discovered  ? 

For  what  purpose  may  this  compound  be  employed  in  the  arts  ? 

In  whit  situation  has  this  substance  been  found  in  nature? 

What  is  the  colour  of  selenium? 


METALLIC  ELEMENTS.  133 

of  sulphur,  but  of  a  red  colour.  When  heated  in  the  flame  of  a 
candle  by  a  stream  of  air  from  a  blowpipe,  it  yields  a  peculiar  strong 
smell,  resembling  that  of  horseradish.  It  presents  some  analogies 
with  sulphur,  but  is  about  double  the  specific  gravity  of  that  sub- 
stance, and  is  a  non-electric,  whence  some  chemists  have  been 
disposed  to  reckon  it  among  the  metals.  It  differs  from  bodies  of 
that  kind,  however,  in  being  a  non-conductor  of  electricity,  and  a 
very  imperfect  conductor  of  heat. 

354.  With  oxygen  selenium  forms  at  least  two  compounds,  one 
called  selenious  acid  and  the  other  selenic  acid. 

Selenious  acid. — When  a  current  of  oxygen  gas  is  passed  over 
selenium  heated  to  its  boiling-point,  it  burns  with  a  pale  blue- 
green  flame,  and  this  acid  sublimes,  and  may  be  condensed  if 
received  in  a  cold  vessel,  forming  long,  brilliant,  prismatic 
crystals.  It  has  a  hot,  sour  taste,  and  a  sharp  odour.  It  dissolves 
in  warm  water,  and  also  in  alcohol.  It  forms  precipitates  in  the 
solutions  of  silver  and  of  lead,  and  combines  in  various  proportions 
with  several  salifiable  bases. 

355.  Selenic  acid  may  be  obtained  by  dissolving  one  part  of 
selenium  in  three  or  four  parts  of  pure  nitric  acid,  and  the  mixture 
being  boiled,  the  selenium  will  decompose  the  nitric  acid,  and  a 
solution  of  selenic  acid  will  be  formed,  which  may  be  evaporated 
to  dryness  in  a  porcelain  capsule  ;   or  if  the  solution  be  only  con- 
centrated, the  acid  will  crystallize  in  hexaedral  prisms.      Selenic 
acid  has  no  smell,  but  a  strong  sour  taste.     It  powerfully  attracts 
water,  and  gives  out  much  heat  when  mixed  with  it.      It  reddens 
vegetable  blues,  and  when  exposed  to  heat  it  becomes  volatilized 
without  decomposition.     When  it  is  boiled  with  muriatic  acid, 
selenious  acid  and  chlorine  are  evolved,  and  the  selenio-muriatic 
acid  which  is  formed  dissolves  gold  in  the  same  manner  with 
the  nitro-muriatic.  Zinc  and  iron  are  dissolved  by  this  acid,  while 
hydrogen  is  given  off;  and  copper  dissolves  with  the  production 
of  selenious  acid.     It  likewise  dissolves  gold,  but  not  platina. 
The  affinity  of  selenic  acid  for  the  salifiable  bases  appears  to  be 
little  inferior  to  that  of  sulphuric  acid  ;  but  the  compounds  it  forms 
with  them  require  further  examination. 

•356.  Selenium  forms  two  compounds  with  chlorine.  Protochlo- 
rlde  of  selenium,  which  may  be  obtained  by  passing  chlorine  gas 
over  selenium,  is  a  brown  liquid,  heavier  than  water;  and  when 
exposed  to  the  action  of  water,  decomposition  takes  place,  and 
muriatic  and  selenious  acids  are  formed.  The  protochloride  may  be 
changed,  by  the  addition  of  chlorine,  into  perchloride,  which  is 

How  is  it  effected  by  heat  ? 

How  does  it  compare  with  sulphur  in  specific  gravity  ? 
How  many  compounds  does  it  form  with  oxygen  ? 
What  are  the  peculiar  properties  of  selenious  acid  ? 
How  is  selenic  acid  obtained  ? 
What  chemical  effects  does  this  acid  exhibit  ? 
With  what  metals  does  it  enter  into  combination  ? 
How  many  compounds  does  selenium  form  with  chlorine  ? 
What  is  the  character  and  composition  of  the  protochloride  ? 
M 


t' 

134  CHEMISTRY. 

a  white,  solid,  crystallizable  substance,  forming  with  water  a 
colourless  sour  solution. 

357.  Selenium  likewise  combines  with  hydrogen,  forming  a 
gaseous  compound  termed  hydroselenic  acid,  or  sdeniuretted  hy- 
drogen. It  may  be  most  readily  obtained  by  dissolving  seleniuret 
of  iron  in  muriatic  acid.  The  compound  dissolves  in  water,  and 
the  solution,  which  gradually  acquires  a  reddish  tint,  has  some- 
what the  smell  and  taste  of  sulphuretted  hydrogen :  it  reddens 
litmus  paper,  and  communicates  a  brown  tint  to  the  skin.  Hy- 
droselenic acid  is  readily  decomposed  by  the  combined  action 
of  air  and  water;  and  it  is  therefore  absorbed  by  moist  substances, 
to  which  it  gives  a  red  colour.  A  thin  mass  of  caoutchouc  may 
thus  be  stained  red  throughout  its  substance.  This  -gas  acts 
most  injuriously  on  the  mucous  membranes;  and  therefore  the 
eyes,  nose,  and  trachea,  should  be  carefully  guarded  against  its 
reception,  while  making  experiments  on  it,  as  its  operation  is 
not  only  painfully  stimulating,  but  might  also  be  productive  of 
serious  mischief. 


METALLIC  ELEMENTS. 

358.  The  metals  form  in  some  respects  a  heterogeneous  collec- 
tion of  substances  :  among  them  are*to  be  found  the  heaviest 
bodies  with  which  we  are  acquainted,  gold  and  platina;  while,  on 
the  contrary,  potassium  and  sodium  are  inferior  in  specific  gravity 
to  water;  gold,  silver,  platina,  and  palladium,  are  in  the  highest 
degree  malleable  and  ductile;  but  antimony,  cobalt,  manganese, 
and  arsenic,  with  some  others,  are  so  brittle  that  they  may  be 
reduced  to  powder  by  percussion.     The  metals  also  differ  greatly 
one  from  another  in  hardness,  colour,  and  capacity  for  yielding 
sound  ;  and  though  they  are  all  conductors  of  heat  and  electricity, 
they  vary  as  to  their  relative  power  of  conduction.     Mercury,  as. 
is  well  known,  is  at  the  common  temperature  of  the  atmosphere  a 
liquid,  and  it  requires  a  degree  of  cold  far  below  that  of  freezing 
water  to  reduce  it  to  the  solid  state :  platina  has  the  opposite 
property  of  remaining  solid  when  exposed  to  the  utmost  heat  of  a 
smelting  furnace,  though  it  may  be  fused  by  the  flame  of  an  oxy- 
hydrogen  blowpipe,  or  by  means  of  a  Voltaic  battery. 

359.  Other  metals  display  intermediate  degrees  of  fusibility  ; 
thus  potassium  and  sodium  melt  at  temperatures  below  that  of 
boiling  water,  tin  becomes  fused  at  442°  Fahrenheit,  bismuth  at 
497°,  and  lead  at  612°;  and  an  alloy  composed  of  these  three 
metals  in  certain  proportions,  dissolves  at  the  boiling-point   of 
water.     It  appears  probable  that  silver  melts  at  2194°,  gold  at 

What  compound  may  selenium  produce  with  hydrogen? 
How  is  it  obtained,  and  what  are  its  characters? 
What  effects  does  it  produce  on  the  animal  system  ? 
What  diversities  in  character  are  ibund  among  the  metals? 
What  are  some  of  the  striking  diversities  in  the  melting  points  of  differ- 
ent metals  ? 


CLASSIFICATION  OF  METALS.  135 

2590°,  copper  at  2842°,  cast  iron  at  3080°,  and,  according  to  MM. 
Clement  and  Desormes,  soft  or  pure  iron  at  3945°,*  but  these 
last  estimates  are  rendered  somewhat  questionable  by  the  difficulty 
of  measuring  the  temperature  of  intensely  heated  bodies. 

360.  As  to  their  decidedly  chemical  properties,  the  metals  ex- 
hibit much  diversity.     All  of  them  are  capable  of  entering  into 
combination  with  oxygen,  chlorine,  and  sulphur ;   but  in  their 
respective  modes  of  action,  and  the  results  of  their  several  affini- 
ties for  those  bodies,  they  manifest  as  much  contrariety  as  with 
regard  to  their  physical  properties. 

361.  Some  metals  have  so  strong  an  attraction  for  oxygen  that 
they  decompose  water  at  all  temperatures,  and  become  oxidated 
by  mere  exposure  to  atmospheric  air,  as  is  the  case  with  potas- 
sium, sodium,  and  calcium  ;  others  decompose  water  but  slowly, 
except  at  a  red  heat,  as  manganese,  zinc,  and  iron.    There  are 

With  what  bodies  do  all  the  metals  combine  ? 

What  circumstances  vary  in  their  respective  modes  of  combining? 

*  The  melting  points  of  silver,  copper,  and  cast  iron,  are  given  from  ex- 
periments with  the  steam  pyrometer.  For  other  temperatures,  see  Scientific 
Class  Book,  pt  i.  p.  299,  in  which  Mr.  Daniell's  first  determinations  are 
given.  His  more  recent  experiments  were,  we  conceive,  liable  to  objection 
from  the  imperfect  exposure  of  his  pyrometer  to  the  melted  mass.  By 
those  experiments,  however,  he  has  given  the  melting  point  of  silver  1873  , 
instead  of  2233°,  as  at  first  published ;  while  Mr.  Prinsep,  by  means  of  a 
gold  bulb  air  thermometer,  obtained  (as  he  supposed)  from  a  mean  of  8  ex- 
periments, the  temperature  of  1825°  for  the  melting  point  of  silver,  but  the 
increasing  rate  of  expansion  in  his  gold  bulb  could  not  be  correctly  allowed 
for,  and  he  moreover  applies  an  erroneous  principle  to  calculate  the  tem- 
perature of  the  expanded  air  ;  the  latter  may  be  corrected.  Then  one  of 
his  experiments,  his  25th,  which  he  terms  a  "silver  melting-heat,"  gives 
2155°.  The  highest  of  Mr.  Prinsep's  8  experiments  on  which  he  relies, 
gives,  according  to  his  method  of  calculating,  1958°,  and  the  lowest  1718°; 
while  of  three  others  which  he  rejects,  without,  it  is  believed,  assigning 
any  adequate  cause  for  the  discrepancy,  the  highest  gave  2358°  and  the 
lowest  2104°.  The  number  assigned  in  the  text  as  the  melting  point  of 
silver,  is  the  mean  of  four  consecutive  experiments,  carefully  made  with  the 
steam-pyrometer,  Aug.  26.  1834,  the  highest  result  being  2293,  and  the 
lowest  2140  degrees. 

Hence  it  appears  that  the  difference  between  Mr.  Daniell's  first 

and  his  second  determination  is  360 

Between  Mr.  Prinsep's,  in  his  adopted  series,  it  is   240° 

In  his  rejected  series  itself   254° 

Between  his  very  highest  and  very  lowest   640° 

IH  the  series  with  the  steam  pyrometer  above  referred  to   153°" 

In  a  series  of  three  experiments  rejected   1 12C 

In  all  those  obtained  by  the  same  instrument  including  the  re- 
jected    296C 

Bringing  together  the  determinations. 

The  first  of  Mr.  Daniell's  is 2233° 

Mr.  Prinsep's  25th  experiment,  rightly  calculated,  but  without 

allowance  for  the  expansion  of  gold    2155° 

Mean  of  4  experiments  with  steam  pyrometer   2194° 

Mean  of  these  3  sets 2194° 

ED. 


136  CHEMISTRY. 

several  others,  including  arsenic,  bismuth,  copper,  and  cobalt, 
which  are  incapable  of  decomposing  water  at  any  temperature, 
but  they  absorb  oxygen  from  the  air  when  strongly  heated.  Mer- 
cury, lead,  nickel,  and  osmium,  do  not  decompose  water,  but  be- 
come oxidated  at  certain  temperatures;  and  when  their  oxides  are 
more  intensely  heated,  they  are  partially  or  wholly  reduced  to  the 
metallic  state.  And  there  is  yet  another  class  of  metals,  which 
neither  abstract  oxygen  from  air  or  water  at  any  temperature,  as 
platina,  gold,  silver,  and  palladium;  and  which,  when  their  oxi- 
dation has  been  effected  indirectly  by  means  of  certain  acids,  are 
reduced  to  the  metallic  state  at  a  heat  below  redness. 

362.  The  method  of  classification  proposed  by  Professor  Ber- 
zelius,  drawn  from  the  electro-negative  and  electro-positive  pro- 
perties of  the  metals  respectively,  when  it  becomes  completely  de- 
veloped, will  present  the  greatest  advantages;  and  it  has  already 
been  applied  to  the  arrangement  of  native  mineral   compounds 
with  great  success,  contributing  much  to  the  elucidation  of  their 
nature,  and  their  relations  to  various  other  bodies. 

363.  Connected  with  this  distinction  of  the  metals  into  those 
which  are  electro-negative  and  those  which  are  electro-positive, 
is  that  which  may  be  deduced  from  the  character  of  their  com- 
pounds.   The  electro-negative  metallic  bodies,  arsenic,  tellurium, 
vanadium,  and  others,  when  united  with  a  relatively  large  propor- 
tion of  oxygen,  constitute  bodies  which  display  the  general  pro- 
perties of  acids,  forming  sur-compounds,  (salts,)  with  metallic 
oxides.  Among  the  electro-positive  metals,  are  those  whose  com- 
binations with  oxygen  most  decidedly  act  the  part  of  bases  in  the 
formation  of  salts.     Hence  all  the  metals  now  known  may  be 
distributed  into  three  classes  :   1.  Those  which  form  acids  with 
oxygen,  namely,  arsenic,  antimony,  columbium,  titanium,  chrome, 
molybdenum   tellurium,   tungsten,    vanadium,    uranium,  manga- 
nese, cobalt,  and  tin.     2.  The  metallic  bases  of  the  alkalies  and 
earths,  potassium,  sodium,  lithium,  baryum,  calcium,  strontium, 
magnesium,  aluminum,  zirconium,  glucinum,  yttrium  or  ittrium, 
and  thorium.     3.  Those  metals  whose  combinations  with  oxygen 
are  not  regarded  as  acids,  alkalies,  or  earths,  namely,  iron,  nickel, 
zinc,  cadmium,  cerium,  lead,  copper,  bismuth,  mercury,  silver, 
gold,  platina,  palladium,  rhodium,  iridium,  and  osmium. 

364.  This  is  to  be  considered  as  only  a  provisional  arrangement, 
admitting  of  alteration  to  suit  it  to  the  future  progress  of  disco- 
very.   Some  of  the  metals  of  the  third  class,  perhaps,  ought  even 
now  to  be  transferred  to  the  first,  as  gold,  the  peroxide  of  which 
is  capable  of  combination  with  barytes,  and  has  therefore  by  some 

What  examples  occur  among  the  metals  in  which  they  become  oxidized 
at  certain  temperatures,  but  give  up  their  oxygen  at  higher  points? 

What  distinction  of  the  metals  has  been  made  by  Berzelius  ? 

What  distinction  of  them  is  founded  on  the  character  of  their  com- 
pounds ?  What  metals  form  acids  with  oxygen  ? 

What  ones  form  earths  and  alkalies  ? 

What  are  those  which  with  oxygen  simply  form  oxides  ? 


ON-METALLIC  ELEMENTS.  137 

been  styled  auric  acid.  The  distinction  between  some  of  the 
metals  of  the  second  and  third  classes  also  is  but  inconsiderable. 
The  characters  of  the  bodies  in  the  first  and  second  classes  are 
sufficiently  contrasted  ;  and  it  is  not  improbable  that  those  of  the 
third  class  may  be  ultimately  found  to  be  referable  to  one  or  other 
of  the  former  classes. 


365.  Binary  Combinations  of  the  Metallic  Elements  of  the  First  Class 
with  Oxygen,  Sulphur,  and  some  other  Non-metallic  Elements. 

Arsenic. 

Arsenious  acid,  2  Ars.  3  Ox. 

Arsenic  acid,  2  Ars.  5  Ox. 

Arseniuretted  hydrogen. 

Red  sulphuret  of  A.,  (Realgar,)  2  Ars.  2  S. 

Yellow  sulphuret  of  A.  (Orpiment,)  2  Ars.  3  S. 

Persulphuret  of  A.,  2  Ars.  5  S. 

Chloride  of  A.,  2  Ars.  3  Ch. 

Perchloride  of  A.,  2  Ars.  5  Ch. 

Antimony. 

Oxide  of  A.,  2  Ant.  3  Ox. 
Antimonious  acid,  2  Ant.  4  Ox. 
Antimonic  acid,  2  Ant.  5  Ox. 
Subsulphuret  of  A.,  2  Ant.,  3  S. 
Sulphuret  of  A.,  2  Ant.  4  S. 
Persulphnret  of  A.,  2  Ant.  5  S. 
Subchloride  of  A.,  2  Ant.  3  Ch. 
Chloride  of  A.,  2  Ant.  4  Ch. 
Perchloride  of  A.,  2  Ant.  5  Ch. 

Columbium. 

Oxide  of  C.,  1  Col.  2  Ox. 
Columbic  acid,  1  Col.  3  Ox. 
Sulphuret  of  C.,  1  Col.  3  S. 
Chloride  of  C.,  1  Col.  3  Ch. 

Titanium. 

Oxide  of  T. 

Titanic  acid,  1  Tit.  2  Ox. 
Sulphuret  of  T.,  1  Tit.  2  S. 
Chloride  of  T.,  1  Tit.  2  Ch. 


ay 

Repeat  the  list  of  metallic  elements  of  the  first  class. 
Name  the  several  compounds  of  arsenic  ? — of  antimony? 
What  are  the  names  and  constituents  of  the  compounds  of  columbium  ? 
of  titanium  ? 

M2 


138  CHEMISTRY. 

Chrome. 

Oxide  of  C.,  2  Chr.  3  Ox. 
Deutoxide  of  C.,  1  Chr.  2  Ox 
Chromic  acid,  1  Chr.  3  Ox. 
Sulphuret  of  C. 

Molybdenum. 

Oxide  of  M.,  1  Mol.  1  Ox. 
Peroxide  of  M.,  1  Mol.  2  Ox. 
Molybdic  acid,  1  Mol.  3  Ox. 
Sulphuret  of  M. 
Chloride  of  M.,  1  Mol.  1  Ch. 
Bichloride  of  M.,  1  Mol.  2  Ch. 
Perchloride  of  M.,  1  Mol.  3  Ch. 

Tellurium. 

Tellurous  acid,  1  Tel.  2  Ox. 
Telluric  acid,  1  Tel.  3  Ox. 
Telluret  of  hydrogen,  1  Tel.  1  H. 
Sulphuret  of  T.,  1  Tel.  2  S. 
Persulphuret  of  T.,  1  Tel.  3  S. 
Chloride  of  T.,  1  Tel.  1  Ch. 
Bichloride  of  T.,  1  Tel.  2  Ch. 

Tungsten. 

Oxide  of  tungsten,  1  Tun.  2.  Ox. 
Tungstic,  or     7  ,  T       «  OY 
Scheelic  acid,  5 
Sulphuret  of  T.,  1  Tun.  2  S. 
Persulphuret  of  T.,  1  Tun.  3  S. 
Chloride  of  T.,  1  Tun.  2  Ch. 
Perchloride  of  T.,  1  Tun.  3  Ch. 

Vanadium. 

Oxide  of  V.,  1  V.  1  Ox. 
Peroxide  of  V.,  1  V.  2  Ox. 
Vanadic  acid,  1  V.  3  Ox. 
Sulphuret  of  V.,  1  V.  2  S. 
Persulphuret  of  V.,  1  V.  3  S. 
Chloride  of  V.,  1  V.  2  Ch. 
Perchloride  of  V.,  1  V.  3  Ch. 

Uranium. 

Oxide  of  U.,  I  U.  1  Ox. 
Uranic  acid,  or  >  9  n   ~  Ov 
Peroxide  of  U.J2U'3 
Sulphuret  of  U.,  2  U.  3  S. 

What  are  the  names  and  constituents  of  the  compounds  of  chrome  ?— of 
molybdenum  ? — of  tellurium  ? — of  tungsten  ? — of  vanadium?— of  uranium  ? 


ARSENIC.  139 

Manganese. 

I  Man.  1  Ox. 
1  Man.  2  Ox. 

Oxides  of  M.^'  2  Man.  3  Ox. 
3  Man.  4  Ox. 
Man.  7  Ox. 
Manganeseous  acid,  1  Man.  3  Ox. 
Manganesic  acid,  2  Man.  7.  Ox. 
Chloride  of  M.,  1  Man.  1  Ch. 
Perchloride  of  M. 
Sulphuret  of  M.,  1  Man.  1  S. 

Cobalt. 

Oxide  of  C.,  I  Cob.  1  Ox. 
Peroxide  of  C.,  2  Cob.  3  Ox. 
Cobaltic  acid,  1  Cob.  2  Ox. 
Chloride  of  C.,  1  Cob.  1  Ch. 
Sulphuret  of  C.,  1  Cob.  1  S. 
Persulphuret  of  C.,  1  Cob.  2  S. 

Tin. 

Oxide  of  T.,  1  Tn.  1  Ox. 
Stannic  acid,  or}.  T     Q  o 
Peroxide  of  T.    $l 
Hemichloride  of  T.,  2  Tn.  1  Ch. 
Chloride  ofT.,  1  Tn.  1  Ch. 
Bichloride  of  T.,  1  Tn.  2  Ch 
Sulphuret  of  T.,  1  Tn.  1  S. 
Bisulphuret  of  T.,  1  Tn.  2  S. 
Phosphuret  of  T.,  3  Tn.  2  Ph. 

36G.  Jlrsenic. — The  substance  popularly  known  under  the  desig- 
nation of  arsenic,  is  the  arsenious  acid,  one  of  the  compounds  of  the 
metal  with  oxygen.  In  the  metallic  or  uncombined  state  arsenic  is 
of  a  grayish-white  colour,  shining  brightly  when  untarnished  ;  but 
as  it  readily  attracts  oxygen  from  the  air,  its  surface  soon  becomes 
dull  when  exposed  to  it ;  but  it  will  retain  its  lustre  if  kept  under 
water  or  alcohol.  It  is  moderately  hard,  and  very  brittle.  Arsenic 
fuses  readily,  and  becomes  volatilized  if  heated  in  a  close  vessel 
to  about  360°.  When  thrown  on  a  red-hot  iron,  or  otherwise 
heated  in  contact  with  atmospheric  air,  it  burns  with  a  blue  flame, 
subliming  in  the  form  of  a  white  vapour,  having  an  odour  like 
garlic.  The  sublimate,  when  cooled,  crystallizes  in  octaedrons, 
consisting  of  arsenious  acid,  formerly  called  white  oxide  of 
arsenic. 

367.  This  substance,  well  known  as  a  most  virulent  poison, 

What  are  the  names  and  constituents  of  the  compounds  of  manganese  ? 
of  cobalt?— of  tin? 

What  is  the  true  chemical  nature  of  while  arsenic? 
What  are  the  properties  of  metallic  arsenic  ? 


140  CHEMISTRY. 

generally  occurs  in  the  state  of  a  compact  saline  mass,  or  heavy 
white  powder.  It  is  very  sparingly  dissolved  by  cold  water;  but 
100  parts  of  the  boiling  water  will  dissolve  7.77  parts  of  the  acid, 
more  than  half  of  which  remains  suspended  after  the  liquid  be- 
comes cool.  The  arsenic  acid,  which  is  a  deliquescent,  colourless 
substance,  is  also  poisonous.  Arseniuretted  hydrogen  is  a  strongly 
poisonous,  inflammable  gas.  Both  the  sulphurets  of  arsenic  oc- 
cur as  native  minerals.  Arsenic  becomes  inflamed  when  introduced 
in  a  divided  state  into  chlorine  gas,  and  burns  with  great  splendour. 

368.  Antimony. — What  is  termed  crude  antimony  in  commerce 
is  the  sulphuret  of  this  metal,  which  is  found  in  the  native  state. 
Metallic  antimony  is  a  shining,  hard,  and  brittle  substance,  some- 
what the  colour  of  silver.  It  has  a  laminated  and  imperfectly 
crystalline  texture.  When  exposed  to  the  air  it  loses  its  lustre, 
but  is  otherwise  little  altered.  If  rubbed  on  the  fingers,  it  gives 
out  a  peculiar  smell  and  taste.  It  becomes  fused  at  810°,  and 
sublimes  in  a  white  heat,  combining  with  oxygen.  The  powdered 
metal  takes  fire  when  thrown  into  chlorine  gas,  and  burns  with  a 
bright  white  flame.  The  product  is  a  liquid,  which  becomes  con- 
crete at  common  temperatures,  constituting  the  chloride,  formerly 
named,  from  its  consistence,  butter  of  antimony.  The  perchloride 
is  a  volatile,  transparent,  fuming  liquid.  Several  preparations  of 
this  metal  are  used  in  medicine,  of  which  the  best  known  and 
most  valuable  is  emetic  tartar,  or  antimoniated  tartrate  of  potash. 

309.  Columbium. — This  is  a  dark  gray  metal,  very  difficult  of 
fusion,  and  extremely  hard  and  brittle.  It  is  not  altered  by  ex- 
posure to  the  air ;  but  it  burns  at  a  red  heat,  forming  a  whitish 
oxide.  It  is  scarcely  at  all  soluble  in  any  of  the  acids  except  the 
fluoric,  in  which  it  dissolves  with  the  evolution  of  heat,  and  the 
disengagement  of  hydrogen  gas. 

370.  Titanium. — Dr.  Wollaston  found  this  metal  in  the  slag 
of  an  iron  furnace  at  MerthyrTydvil,  in  South  Wales,  in  the  state 
of  small  cubic  crystals,  of  a  red  or  copper  colour,  and  so  hard  as 
to  scratch  rock  crystal.  It  is  infusible  by  a  common  blowpipe, 
but  becomes  oxidated  by  continued  heat,  a  purple  film  forming  on 
its  surface.  No  acid  acts  on  it ;  but  if  it  be  heated  with  nitre, 
oxidation  readily  takes  place.  The  oxide  of  titanium  has  been 
used  for  painting  on  porcelain. 

What  form  has  the  poisonous  compound  when  crystallized  ? 

In  what  proportion  is  it  soluble  in  boiling  water? 

How  does  metallic  arsenic  react  with  chlorine  ? 

Jn  what  form  is  antimony  found  in  commerce  ? 

What  are  the  characters  of  true  metallic  antimony  ? 

At  what  heat  does  it  sublime  ? 

What  is  butter  of  antimony  ? 

For  what  purpose  is  antimony  employed  in  medicine  and  in  what  form? 

What  are  the  exterior  appearances  of  columbium  ? 

How  is  it  affected  by  air  and  heat  ? 

What  solvent  can  act  upon  this  metal  ? 

Where  and  by  whom  was  titanium  discovered  ? 

State  its  chemical  character  and  relations. 


TUNGSTEN.  141 

371.  Chrome,  or  Chromium.  —  This  metal  obtained  its  name  from 
the  varied  colours  of  its  salts.*  It  is  a  white  and  very  brittle  metal, 
susceptible  of  a  high  polish,  and,  according  to  Richter,  slightly 
magnetic.  It  can  be  fused  but  imperfectly  at  a  very  high  tempera- 
ture.    No  acids  appear  to  act  on  it  except  the  fluoric,  which  dis- 
solves it  readily.     When  heated  with  nitre  it  combines  with  oxy- 
gen, forming  chromic  acid.     This  acid  is  of  a  deep  red  colour; 
and  the  oxide  of  chrome  exhibits  a  green  colour.     Some  of  the 
coloured  gems  owe  their  beautiful  tints  to  this  metal  ;  and  it  fur- 
nishes some  fine  pigments  for  enamel  painting  and  calico-printing. 

372.  Molybdenum.  —  This  metal  is  said  to  have  been  obtained  in 
the  state  of  small  grains,  of  a  brittle  texture,  and  of  a  light  gray 
colour  ;  but  it  may  be  questioned  whether  it  has  undergone  per- 
fect reduction,  as  it  is  exceedingly  difficult  of  fusion.     When 
heated  in  contact  with  oxygen  gas,  or  atmospheric  air,  it  becomes 
converted  into  a  white  crystalline  sublimate,  which  is  the  molyb- 
dic  acid. 

373.  Tellurium.  —  This  is  one  of  the  most  important  of  the 
acidifiable  metals,  the  nature  and  properties  of  which  have  been 
illustrated  by  the  elaborate  researches  of  Berzelius.f    The  metal 
is  of  a  bright  gray  colour,  and  has  a  foliated  texture  :  it  is  brittle, 
readily  fusible,  and  very  volatile.     When  heated  to  full  redness 
in  a  close  vessel,  it  sublimes  in  the  form  of  a  yellow  gas,  which 
condenses  in  drops,  and  becomes  crystallized  on  cooling.     The 
smell  of  its  vapour  is  peculiar,  slightly  resembling  that  of  sele- 
nium.ij:     Tellurium  is  soluble  in  the  nitric  and  the  nitro-muriatic 
acids.     Its  combination  with  oxygen  in  the  proportion  of  1  T.+2 
Ox.  forms  an  acid  capable  of  existing  in  two  states,  the  tellurous 
acid  and  the  paratellurous  acid  ;  and  the  compound  of  1  T.-f-3  Ox. 
has  corresponding  properties,  forming  the  telluric  and  the  para- 
telluric  acids.  §     The  combination  of  tellurium  with  hydrogen  is 
a  gas,  which,  like  sulphuretted  hydrogen,  manifests  the  properties 
of  an  acid. 

374.  Tungsten.  —  This  metal  is  distinguished  for  its  specific  gra- 
vity, being  about  17^  that  of  water.  It  is  of  an  iron-gray  colour,  very 
hard,  brittle,  and  difficult  effusion.  When  heated  in  atmospheric 

Whence  does  chromium  derive  its  name  ? 

What  is  its  appearance? 

How  is  chromic  acid  produced  ? 

For  what  purposes  is  it  employed  in  the  arts  ? 

What  change  have  chemists  been  able  to  produce  on  molybdenum  ? 

For  what  properties  is  tellurium  distinguished  ? 

In  what  substances  is  it  soluble  ? 

By  what  circumstance  is  tungsten  distinguished  ? 


*  From  the  Greek  Xpu 

t  See  Johnston  on  Chemistry  in  Report  of  British  Association,  1832,  p. 

t  Id.  p.  472.  The  odour  of  this  metal,  or  rather  of  the  vapour  of  tellu- 
rous acid,  has  been  compared  with  that  of  radishes.  See  Children's  Essay 
on  Chemical  Analysis,  p.  67. 

$  Id.  pp.  472,  473. 


142  CHEMISTRY. 

air,  it  combines  with  oxygen  to  form  tungstie  oxide,  a  brown  or 
chocolate-coloured  powder.  This  oxide  exposed  to  a  red  heat, 
and  agitated  in  an  open  vessel,  absorbs  more  oxygen,  and  becomes 
tungstic  acid,  which  is  a  yellow  powder,  but  acquires  a  greenish 
hue  by  long  exposure  to  the  rays  of  the  sun. 

375.  Vanadium. — The  properties  of  this  metal  most  nearly  cor- 
respond with  those  of  chrome,  and  in  a  natural  arrangement  of 
the  metallic  elements,  it  might  be  placed  between  chrome  and 
molybdenum.     In  colour  and  lustre  it  resembles  the  latter  me- 
tal.    "It  is  characterized  by  giving,  in  the  form  of  an   oxide, 
blue  salts  with  acids;    with   oxygen  forming   a   peculiar  acid, 
which  fuses  at  a  red  heat  without  decomposition,  and  on  cool- 
ing  is   reddish-brown   and   crystalline,   and    which   gives  with 
bases  colourless  neutral  and  orange-coloured  acid  salts.     Before 
the  blowpipe  it  behaves  itself  like  chromium,  with  this  charac- 
teristic difference,  that  the  green  colour  with  borax  can  in  the  oxi- 
dizing flame  be  changed  into  a  pale  yellow.* 

376.  Uranium. — This  metal  is  of  a  grayish-brown  colour,  pos- 
sessing considerable  lustre,  brittle,  and  very  difficult  of  fusion.  It 
does  not  tarnish  in  the  air  at  common  temperatures,  but  when 
made  red-hot  in  an  open  vessel,  it  becomes  oxidated,  forming  a 
dark  green  or  blackish  powder.    The  compound  of  2  U.  -\-  3  Ox., 
is  a  yellow  powder,  used  in  painting  porcelain,  arid  which  acts  as 
an  acid,  forming  a  salt  with  barytes. 

377.  Manganese. — This  metal  in  some  of  its  properties,  resem- 
bles iron.     It  may  be  obtained  by  exposing  the  black  oxide,  with 
charcoal  powder  and  oil,  to  a  most  intense  heat  in  a  wind  furnace, 
and  the  metal  will  then  be  found  in  small  globules,  or  in  the  form 
of  an  imperfect  button,  at  the  bottom  of  the  crucible.     It  is  of  a 
dusky-whitish  colour,  and  finely  granular  texture,  softer  than  cast 
iron,  and  very  brittle.  It  is  difficult  of  fusion,  and  is  readily  acted 
on  by  the  air,  tarnishing,  and  at  length  crumbling  into  a  brown 
powder.     When  heated  in  oxygen  gas,  it  undergoes  combustion, 
and  it  decomposes  the  vapour  of  water  at  a  red  heat.     The  per- 
oxide, 1  M.-J-2  Ox.,  from  its  colour  styled  black  oxide  of  manga- 
nese, is  frequently  found  native,  and  is  the  general  source  from 
which  the  metal  and  its  compounds  are  procured.     No  change  is 
produced  on  it  by  exposure  to  the  air,  but  the  variety  of  native 
oxide,  called  black  wad,  has  the  property  of  spontaneous  inflam- 

What  compounds  of  this  substance  are  formed  with  oxygen  ? 
To  what  metals  is  vanadium  most  nearly  related  ? 
What  two  (Species  of  compounds  does  it  form  with  oxygen  ? 
What  is  the  colour  of  uranium  ? 

What  compound  of  this  metal  is  employed  ^n  the  arts  and  for  what  pur 
pose? 

How  is  manganese  procured  ? 

What  effect  has  air  on  this  metal  ? 

What  ingredient  does  manganese  derive  from  water  ? 

*  See  Johnston's  Rep.  on  Chem.,  p.  469. 


TIN.  143 

mation,  when  well  dried,  and  kneeded  with  linseed  oil.  It  is  in- 
soluble in  water,  and  does  not  combine  with  acids  or  alkalies  ;  but 
such  acids  as  appear  to  dissolve  it,  reduce  it  to  the  state  of  protox- 
ide, with  which  salts  are  formed. 

378.  When  the  peroxide  of  manganese  is  mixed  with  an  equal 
weight  of  nitrate  of  potash,  and  exposed  to  a  red  heat,  a  green 
mass  is  obtained,  which  being  put  into  water,  furnishes  a  solution, 
the  colour  of  which  successively  becomes  green,  blue,  purple,  and 
red,  and  ultimately  disappears  entirely ;  whence  it  has  been  called 
the  chamelion  mineral.     The  experiment  may  be  varied  by  putting 
equal  quantities  of  the  mixture  of  the  peroxide  and  nitre  into  two 
glasses,  and  pouring  on  one  hot,  and  on  the  other  cold  water,  when 
the  former  solution  will  exhibit  a  fine  green  colour,  and  the  latter 
a  deep  purple,  and  the  shades  will  vary  with  the  alteration  of 
temperature.* 

379.  Cobalt. — The  metallic  nature  of  this  substance  was  first 
recognized  about  one  hundred  years  ago,  but  its  oxide  has  been 
used  in  making  coloured  glass  since  1540.     Cobalt  is  of  a  red- 
dish-gray colour,  and  a  fibrous  or  laminated  texture,  brittle,  and 
difficultly  fusible.     Like  iron  and  nickel,  it  may  be  rendered  mag- 
netic.    Neither  air  nor  water  acts  on  it  at  a  low  temperature,  but 
when  heated  to  redness  in  an  open  vessel,  it  forms  an  oxide  of  a 
very  deep  blue  colour,  and  if  the  heat  be  intense,  the  metal  takes 
fire  and  burns  with  a  red  flame.  The  chloride  of  cobalt,  combined 
with  water,  forms  Hellot's  sympathetic  ink,  which  may  be  pre- 
pared by  digesting  the  oxide  of  this  metal  in  muriatic  acid,  and 
adding  water  till  the  liquid  becomes  of  a  pale  rose  colour.     Any 
thing  written  on  paper  with  a  clean  pen  dipped  in  this  solution, 
will  be  invisible  till  it  is  slightly  heated,  when  the  writing  will 
appear  of  a  bright  green  tint,  which  vanishes  as  the  paper  cools, 
and  may  be  renewed  at  pleasure  ;  but  if  once  strongly  heated,  the 
characters  become  permanent.     Acetate  of  cobalt  (the  salt  formed 
by  oxide  of  cobalt  and  acetic  acid)  dissolved  in  water  constitutes 
an  excellent  sympathetic  ink,  which  may  be  used  like  the  preced- 
ing; but  it  gives  to  paper  a  beautiful  azure  instead  of  a  green 
tint  when  heated.     The  oxide  of  cobalt,  in  combinations  with  si- 
licic acid  and  potash,  forms  smalt,  and  other  blue  pigments  used 
in  the  arts. 

380.  Tin. — This  is  one  of  the  metals  which  appear  to  have 
been  known  to  the  ancient  Greeks  and  Romans,  who  obtained  it 

What  is  the  nature  of  the  action  of  acids  on  the  black  oxide  of  manga- 
nese? 

How  is  chameleon  mineral  obtained  ? 

How  may  the  influence  of  temperature  on  chemical  effects  be  illustrated 
by  this  substance  ? 

How  long  has  cobalt  been  known  as  a  metal  ? 

What  temperature  is  necessary  to  effect  its  combustion  ? 

What  is  the  composition  and  use  of  Hellot's  sympathetic  ink  ? 

What  other  compound  of  cobalt  produces  similar  effects? 

*  See  Johnston's  Rep.  on  Chem.,  pp.  477,  482 


144  CHEMISTRY. 

from  Spain  and  Britain.  Its  general  appearance  is  well  known, 
tin-plate,  consisting  of  sheets  of  iron  coated  with  tin,  being  used 
for  a  multiplicity  of  purposes ;  and  tinfoil,  (leaf-tin,)  employed 
to  line  tea-chests,  and  wrap  up  articles  which  require  to  be  pro- 
tected from  the  air.  Tin  is  not  very  hard  nor  ductile,  but  ex- 
tremely malleable  ;  and  when  sheet-tin  is  bent  suddenly,  it  emits  a 
peculiar  sound,  called  by  the  French  cri  d'etain :  this  metal  has  also 
a  characteristic  odour,  and  a  faint  but  disagreeable  taste.  It  is 
not  affected  by  water  at  common  temperatures,  but  becomes 
tarnished  by  exposure  to  the  air.  If  steam  be  passed  over  tin 
heated  to  redness,  it  decomposes  the  water,  absorbing  oxygen, 
and  the  hydrogen  is. given  off  in  the  gaseous  state.  The  compound 
of  1  T.  +  2  Ox.,  called  peroxide  of  tin,  is  capable  of  combination 
with  alkalies,  thus  manifesting  the  properties  of  an  acid.  When 
fused  with  glass,  it  forms  a  milk-white  enamel,  useful  for  technical 
purposes. 

381.  The  substance  called  in  commerce  tin  putty,  is  an  impure 
oxide  of  tin.  This  metal  burns  in  oxygen  gas,  when  heated 
below  its  fusing-point,  and  it  is  soluble  in  the  sulphuric,  nitric, 
and  muriatic  acids.  Bichloride  of  tin  is  a  colourless  liquid,  called 
the  fuming  liquor  of  Libavius,  from  its  alleged  discoverer,  a 
chemist  of  the  seventeenth  century.  Combinations  of  tin  with 
chlorine  are  used  in  dying  and  calico-printing,  and  with  the  solu- 
tion of  gold  in  nitro-muriatic  acid,  to  form  the  purple  powder  of 
cassius,  a  pigment  employed  in  ornamenting  porcelain.  The 
bisulphuret  of  tin  is  a  substance  of  a  shining  yellow  colour,  and  a 
flaky  structure,  which  was  formerly  called  Mosaic  gold  (Jlurum 
Musivum . ) 

Binary  Combinations  of  the  Metallic  Elements  of  the  Sec&nd  Class 
with  Oxygen  and  Chlorine. 

Potassium. 

Protoxide  of  P.,  (potash,)  1  Pm.  1  Ox. 
"    Peroxide  of  P.,  1  Pm.  3  Ox. 
Chloride  of  P.,  1  Pm.  1  Ch. 

Sodium. 

Protoxide  of  S.,  (soda,)  1  Sod.  1  Ox. 

Peroxide  of  S.,  1  Sod.  2  Ox. 

Chloride  of  S.,  (marine  salt,)  1  Sod.  1  Ch. 

What  properties  does  tin  possess  in  a  high  degree  ? 

How  does  it  react  on  the  vapour  of  water  ? 

What  compound  of  tin  manifests  acid  properties  ? 

What  is  meant  by  tin  putty  ? 

What  peculiar  characters  has  the  perchloride  of  tin  ? 

What  was  it  formerly  called  ? 

Of  what  is  powder  of  cassius  composed  ? 

What  is  the  nature  of  Mosaic  gold  ? 

Repeat  the  list  of  metallic  elements  of  the  second  class. 

What  are  the  compounds  formed  with  potassium  ? — with  sodium  ? 


POTASSIUM.  145 

Lithium. 

Oxide  of  L.,  (lithia,)  1  L.  1  Ox. 
Chloride  of  L  ,  1  L.  1  Ch. 

Baryum. 

Protoxide  of  B.,  (barytes,)  1  B.  1  Ox. 
Peroxide  of  B.,  1  B.  2  Ox. 
Chloride  of  B.,  1  B.  1  Ch. 

Calcium. 

Protoxide  of  C.,  (lime,)  1  Cal.  1  Ox. 

Peroxide  of  C.,  1  Cal.  2  Ox. 

Chloride  of  C.,  (muriate  of  lime,)  1  Cal.  1  Ch. 

Strontium. 

Protoxide  of  S.,  (strontia,)  1  Str.  1  Ox. 
Peroxide  of  S.,  1  Str.  2  Ox. 
Chloride  of  S.,  1  Str.  1  Ch. 

Magnesium. 

Oxide  of  M.,  (magnesia,)  1  Mag.  1  Ox. 
Chloride  of  M.,  1  Mag.  1  Ch. 

Aluminum. 

Oxide  of  A.,  (alumina,)  2  Al.  3  Ox. 
Chloride  of  A.,  2  Al.  3  Ch. 

Zirconium. 

Oxide  of  Z.,  (zircon  earth,)  2  Zir.  3  Ox. 

Glucinum. 

Oxide  of  G.,  (glucina,)  2  Gl.  3  Ox. 

Yttrium.  ^ 

Oxide  of  Y.,  (yttria,)  1  Y.  1  Ox. 

Thorium. 

Oxide  of  T.,  (thorina,)  1  Th.  1  Ox. 

383.  Potassium. — This  metal  is  the  basis  of  potassa,  or,  as  it 
was  formerly  called,  the  fixed  vegetable  alkali,  which  was  dis- 
covered by  Sir  H.  Davy  to  be  protoxide  of  potassium.  It  may  be 
procured  by  placing  a  thin  plate  of  pure  caustic  potash,  slightly 

What  are  the  compounds  formed  with  lithium? — baryum  ? — calcium? 
strontium  ? — magnesium  ? — aluminum  ? — zirconium  ?— glucinum  ?--yttrium  ? 
thorium  ? 

What  is  the  chemical  nature  of  potassa  ? 


146  CHEMISTRY. 

moistened,  between  two  disks  of  platina,  connected  with  the  op- 
posite wires  of  a  powerful  Voltaic  battery,  when  the  alkali  will 
become  fused  and  afterwards  decomposed,  its  oxygen  being 
evolved  at  the  positive  wire,  while  the  metal,  in  small  shining 
globules,  will  make  its  appearance  at  the  surface  connected  with 
the  negative  wire.  Potassium  may  also  be  obtained  by  passing 
melted  potash  through  a  red-hot  gun-barrel,  containing  fragments 
of  iron,  which,  at  a  very  high  temperature,  will  decompose  the 
alkali,  by  attracting  its  oxygen,  and  thus  the  metal  will  be  set 
free  as  before.  The  affinity  of  this  metal  with  oxygen  is  so  great, 
that  it  decomposes  most  bodies  which  contain  it,  even  at  very  low 
temperatures ;  and  hence  when  potassium  comes  in  contact  with 
atmospheric  air  or  water,  it  immediately  absorbs  oxygen  from 
either  of  those  fluids,  and  protoxide  of  potassium  or  .potash  is  thus 
produced.  Potassium,  therefore,  cannot  be  preserved  without 
being  secured  from  the  contact  of  air  and  water ;  but  it  may  be 
kept  immersed  in  ether,  or  included  in  exhausted  glass  tubes 
hermetically  sealed. 

384.  Potassium  at  32°  Fahrenheit,  is  a  hard,  brittle  solid,  of  a 
crystalline  structure,  and  of  a  white  colour,  like  silver.     At  about 
50°  it  becomes  malleable  and  ductile,  having  nearly  the  consistency 
of  soft  wax,  and  in  that  state  its  specific  gravity  is  about  0.85 ; 
at  150°  it  is  perfectly  fluid,  and  at  a  bright  red  heat  it  sublimes 
without  decomposition,  in  the  form  of  a  green  vapour.    It  is  a  good 
conductor,  both  of  heat  and  electricity.      When  this  metal  is 
heated  in  air  or  oxygen  gas,  it  burns  with  a  brilliant  white  flame, 
and  is  converted  into   an  orange-coloured  substance,  which,  on 
cooling,  appears  in  the  state  of  crystalline  scales.     This  is  the 
peroxide  of  potassium.     The  protoxide  of  potassium,  or  caustic 
potash,  has  a  most  powerful  affinity  for  water,  which  it  readily 
absorbs  from  the  air;  and  thus  forms  a  definite  compound,  called 
hydrate  of  potash,  composed  of  1  potash -f-  1  water. 

385.  The  common  potash  and  pearlash  of  the  shops  consist  of 
this  alkali  combined  with  carbonic  acid,  forming   carbonate  of 
potash.     This  salt  is  commonly  obtained  by  evaporating  the  ley 
produced  by  steeping  wood-ashes  in  water.      The  decomposition 
of  the  carbonate  of  potash  is  effected  by  means  of  caustic  lime, 
which  having  a  stronger  attraction  for  carbonic  acid  than  potash 
has,  it  attracts  the  acid,  and  sets  free  the  alkali  in  the  state  of 
hydrate  of  potash.   This  substance,  when  purified,  is  white,  acrid, 

How  is  its  metallic  base  procured  ? 

In  what  manner  may  it  be  obtained  from  the  reaction  of  potassa  with 
iron? 

In  what  manner  must  potassium  be  preserved  ?     Why  ? 
What  characters  does  potassium  exhibit  at  low  temperatures? 
At  what  temperature  does  it  become  ductile  ? 
What  is  its  melting  point  ? 
At  what  point  is  it  vaporized  ? 

What  compounds  does  potassium  form  by  combustion  in  oxygen  ? 
What  is  the  chemical  nature  of  pearlash T? 


SODIUM.  147 

and  corrosive,  destroying  the  texture  of  animal  and  vegetable  sub- 
stances. It  speedily  absorbs  moisture  and  carbonic  acid  from  the 
air,  but  it  may  be  crystallized  in  octaedrons,  by  keeping  a  strong 
solution  of  it  in  water  for  some  time,  in  close  vessels.  It  reddens 
substances  coloured  by  turmeric,  changes  vegetable  blues  to  green, 
and  neutralizes  acids  without  any  effervescence.  It  enters  into 
combination  with  fat  oils,  forming  soft  soaps. 

386.  When  small  quantities  of  potassium  are  introduced  into 
chlorine  gas,  intense  inflammation  takes  place,  and  the  chloride 
is   produced.      This   is   a   white   saline   substance,  of  a  bitter, 
disagreeable  taste,  readily  soluble  in  water,  from  which  it  may  be 
procured  by  evaporation  in  cubic  crystals.     It  was  formerly  sup- 
posed to  be  a  compound  of  muriatic  acid  and  potash,  and  it  was 
long  used  in  medicine  under  the  names  of  digestive  salt  of  Sylvius, 
and  regenerated  sea-salt.     Potassium  has  a  stronger  affinity  for 
chlorine  than  for  oxygen,  since  both  its  oxides  are  decomposed  by 
chlorine  gas. 

387.  Potassium  enters  into  combination  with  iodine  and  with  bro- 
mine, and  the  iodide  of  potassium  is  sometimes  used  in  medicine. 
Potassium  also  unites  with  hydrogen,  sulphur,  selenium,  phos- 
phorus, and  carbon,  to  form  peculiar  compounds.      Alloys   are 
formed  by  the  combination  of  potassium  with  various  other  metal- 
lic bodies.     The  amalgam  of  potassium,  or  combination  of  this 
substance  with  mercury,  may  be  readily  formed,  by  mixing  them 
together  at  the  usual  temperature  of  the  air.     This  amalgam  may 
also  be  produced  by  placing  a  thin  mass  of  mercury  in  the  bottom 
of  a  flat  glass  vessel,  about  two  inches  in  diameter,  and  pouring 
over  it  a  strong  solution  of  caustic  potash,  then  on  connecting  an 
iron  wire  from  the  negative  pole  of  a  Voltaic  battery  with  the 
mercury,  and  a  platina  wire  from  the  positive  pole  with  the  alkaline 
solution,  into  which  it  must  be  dipped  so  as  not  to  touch  the  surface 
of  the  mercury,  an  amalgam  will  be  formed  with  such  rapidity, 
that  more  than  1200  grains  of  mercury  will  become  combined  into 
a  solid  alloy  with  the  potash  in  twenty-four  hours.  This  amalgam 
has  the  property  of  dissolving  all  other  metals.     Potassium  like- 
wise combines  with  gold,  silver,  and  copper;  but  when  any  of  its 
alloys  are  thrown  into  water  they  become  decomposed,  potash 
being  formed,  which  dissolves  in  the  water,  and  the  other  metal 
is  set  free. 

388.  Sodium. — This  metal,  which  is  the  basis  of  soda  or  mineral 
alkali,  greatly  resembles  potassium,  both  in   its   physical   and 
chemical  properties.     It  may  be  obtained  from  soda  by  similar 
processes  to  those  already  described  for  the  decomposition  of 
potash,  only  it  is  necessary  to  employ  a  stronger  electric  power, 
or  a  higher  degree  of  heat.     Sodium  is  a  soft,  malleable  metal, 

How  is  the  carbonic  acid  separated  from  carbonate  of  potash  ? 
What  are  the  compounds  of  potassium  with  chlorine  ? 
What  peculiar  property  has  the  amalgam  of  potassium  ? 
What  differendfe  are  observable  between  potassium  and  sodium? 


148  CHEMISTRY. 

which  does  not  become  brittle  like  potassium  at  32°,  since  at  thaft 
temperature  globules  of  it  may  be  welded  together  by  pressure 
It  is  rather  heavier  than  potassium,  its  specific  gravity  being  0.97. 
In  colour  it  resembles  lead,  but  tarnishes  on  exposure  to  a  moist 
atmosphere.  Its  fusing-point  is  about  190°,  and  it  is  volatile  at  a 
white  heat ;  but  if  heated  in  contact  with  air,  it  burns  with  a 
white  light,  accompanied  with  red  sparks.  In  consequence  of  its 
powerful  affinity  for  oxygen,  it  must,  like  potassium,  be  preserved 
under  ether  or  naphtha.  Soda,  or  the  protoxide  of  sodium,  com- 
bines with  water,  forming  hydrate  of  soda,  which  is  the  mineral 
alkali  or  natron  of  commerce. 

389.  The  combination  of  sodium  with  chlorine,  (chloride  of  so- 
dium,) is  the  substance  generally  known  as  common  or  marine 
salt.     This  body,  which  exists  largely  in  nature,  especially  in  the 
state  of  rock-salt  and  in  solution  in  sea-water,  was  formerly  sup- 
posed to  be  a  compound  of  muriatic  acid  and  soda,  and  hence  it 
was  called  muriate  of  soda.     It  is  now  known,  however,  to  be  a 
substance  of  a  different  class  from  the  proper  salts,  or  compounds 
of  acids  and  alkalies,  and,  upon  the  whole,  it  may  be  considered 
as  having  a  closer  analogy  with  the  alkalies  than  with  the  neutral 
salts.     It  may  be  produced  artificially  by  heating  sodium  in  chlo- 
rine gas,  when  the  metal  burns,  forming  a  white  compound,  which 
is  the  chloride  of  sodium.    This  chloride  becomes  decomposed  by 
heating  it  with  potassium,  and  thus  the  sodium  is  set  free  and 
chloride  of  potassium  produced. 

390.  If  protoxide  of  sodium  be  exposed   to  heat,  in  chlorine 
gas,  oxygen   will  be  evolved,  and   chloride  of  sodium  formed. 
When  the  protoxide  is  heated  in  hydro-chloric  (muriatic  acid) 
gas,  a  mutual  decomposition  will  take  place,  and  the  products 
will  be  the  chloride  and  water.     The  chloride  of  sodium  crystal- 
lizes in  regular  cubes,  which  decrepitate,  or  fall  into  pieces  with  a 
crackling  noise  when  heated  ;  and  if  the  heat  be  raised  to  redness, 
the  crystals  fuse  without  decomposition,  and  on  cooling  become  con- 
gealed into  a  hard  white  mass.     This  substance,  though  readily 
soluble   in   water,   is   almost  insoluble  in  alcohol.     Its  general 
properties,  and  the  numerous  purposes  to  which  it  is  applied,  are 
too  well  known  to  require  specification. 

391.  Sodium  unites  with  iodine  and  bromine,  and  among  the 
combustibles,  with  sulphur,  selenium,  and  phosphorus,  but  not 
with  hydrogen.     It  forms  alloys  with  most,  if  not  all,  the  metals. 

392.  Lithium. — This  is  a  metallic  substance  comparatively  of 
rare  occurrence,  having  hitherto  been  found  only  in  the  petalite, 
spodumene,  lepidolite,  some  kinds  of  feldspar,  and  a  few  other 
minerals,  and  in  certain  waters  in  Bohemia.      In  these  bodies  it 

What  \9  the  melting  point  of  sodium  ? 

By  what  name  is  hydrate  of  soda  known  in  commerce  ?    What  is  the 
true  chemical  nature  of  common  salt  ?  What  was  it  formerly  supposed  to  be  I 
How  is  common  salt  acted  on  by  potassium,  and  what  are  the  results  ? 
With  which  classes  of  non-metallic  bodies  does  sodium  unite? 
In  what  substances  is  lithia  found  ? 


BARYUM.  149 

exists  in  the  state  of  an  oxide,  called  lithia,  which  exhibits  pro- 
perties partly  resembling  those  of  the  earths,  and  partly  those  of 
the  alkalies.  The  oxide  of  lithium  may  be  decomposed,  like  pot- 
ash and  soda,  by  Voltaic  electricity,  and  the  product  is  a  brilliant 
white  and  highly  combustible  metallic  substance,  bearing  much 
resemblance  to  sodium  ;  but  its  properties  have  hitherto  been  very 
little  investigated,  in  consequence  of  the  scarcity  of  its  compounds. 
Chloride,  iodide,  fluoride,  and  sulphuret  of  lithium,  have  been  ob- 
tained, but  their  respective  properties  are  but  imperfectly  known. 
Oxide  of  lithium  (lithia)  differs  from  potash  and  soda  in  its 
power  of  saturating  a  greater  quantity  of  any  acid,  and  in  forming 
difficultly  soluble  salts  with  the  carbonic  and  phosphoric  acids. 
It  may  be  distinguished  from  the  alkaline  earths  (lime  and  bary- 
tes)  by  the  greater  solubility  of  its  saline  compounds  with  the 
sulphuric  and  oxalic  acids ;  and  by  its  acting  in  the  state  of  car- 
bonate upon  vegetable  colours,  like  potash  and  soda. 

393.  Baryum. — This  metallic  body  may  be  obtained  by  nega- 
tively electrizing  its  oxide  (which  is  the  earth  called  barytes)  in 
contact  with  mercury.  An  amalgam  will  thus  be  gradually  formed, 
from  which  the  mercury  may  be  expelled  by  heat.      The  metal 
is  of  a  dark  gray  colour,  with  a  lustre  inferior  to  that  of  cast- 
iron,  and  it  is  about  twice  as  heavy  as  water.    It  speedily  absorbs 
oxygen  when  exposed  to  air,  crumbling  into  a  white  powder, 
which  is  the  protoxide  of  baryum  :  and  when  thrown  into  water 
it  suddenly  decomposes  that  fluid,  hydrogen  being  evolved,  and 
the  oxide  which  is  formed  dissolving  in  the  water.     The  protox- 
ide of  baryum  (barytes)  is  not  unfrequently  found  among  minerals, 
in  combination  with    either  the  carbonic  or  the  sulphuric  acid, 
with  the  latter  of  which  jt  constitutes  the  substance  called  pon- 
derous spar  (terra  ponderosa.) 

394.  Pure  barytes  has  a  caustic  taste,  turns  vegetable  blue  co- 
lours green,  and  neutrallizes  acids  like  the  alkalies.     It  is  very 
poisonous,  as  likewise  are  all  the  soluble  salts  formed  of  it.     It 
is  usually  obtained  in  the  state  of  a  gray  powder,  the  specific 
gravity  of  which  is  about  4.     It  is  insoluble  in  pure  alcohol,  but 
very  readily  soluble  in  water,  and  it  may  be  slaked  like  quick- 
lime, giving  out  a  great  quantity  of  heat  during  the  process.    Per- 
oxide of  baryum  may  be  produced  by  heating  the  protoxide  in 
oxygen  gas,  which  is  rapidly  absorbed,  and  a  gray  compound  is 
formed.     This  substance  is  principally  deserving  of  notice,  as 
having  been  used  by  M.  Thenard  in  the  preparation  of  oxygenated 
water,  of  which  some  account  has  been  already  given. 

Baryum  unites  with  chlorine,  iodine,  bromine,  and  fluorine,  and 
also  with  some  of  the  simple  combustibles. 

How  does  lithia  differ  from  the  vegetable  and  marine  alkalies  ? 
How  from  lime  and  barytes  ? 
How  is  baryum  procured  ? 

By  what  names  do  mineralogists  distinguish  the  minerals  formed  of  ba- 
ryum ?    .What  sensible  and  other  properties  belong  to  baryum? 
To  what  chemical  purpose  has  the  peroxide  of  baryum  been  applied  ? 

N2 


150  CHEMISTRY. 

395.  Calcium. — This  metal  was  discovered  by  Sir  H.  Davy, 
who  procured  it  in  a  separate  state  from  lime  by  the  action  of  a 
Voltaic  battery.  It  has,  however,  been  obtained  in  very  small 
quantities,  and  but  little  is  known  concerning-  its  physical  proper- 
ties except  that  it  has  the  colour  and  lustre  of  silver.  When  ex- 
posed to  common  air  the  metal  takes  fire,  and  burns  with  an  in- 
tense white  light,  forming  protoxide  of  calcium,  or  pure  lime. 
The  amalgam  of  calcium  thrown  into  water  is  decomposed  with 
the  evolution  of  hydrogen,  and  the  oxygen  of  the  water  unites 
with  the  calcium  to  form  lime.  The  protoxide  of  calcium  (lime) 
is  a  white  pulverulent  earth,  which  is  one  of  the  most  abundant  and 
most  important  of  all  natural  substances.  In  the  mineral  king- 
dom it  forms  limestone  and  other  rocks ;  it  is  contained  in  many 
vegetable  products,  and  also  forms  the  basis  of  bone  and  other 
animal  substances.  It  may  be  most  readily  obtained  in  the  state 
of  purity  by  exposing  powdered  calcareous  spar,  or  white  marble, 
to  a  strong  red  heat. 

3.06.  Pure  lime,  commonly  called  quicklime,  has  an  acrid  and 
alkaline  taste,  corrodes  animal  substances,  and  changes  vegetable 
blue  colours  to  green.  It  is  very  difficultly  fusible,  but  facilitates 
extremely  the  fusion  of  other  mineral  bodies,  as  metallic  ores,  and 
it  is  therefore  employed  as  a  cheap  and  powerful  flux.  It  is 
sparingly  soluble  in  water,  and  hot  water  takes  up  a  smaller 
quantity  of  it  than  cold,  so  that  when  lime-water  is  boiled,  the 
lime  is  precipitated.  Lime  absorbs  moisture  from  the  air,  and 
becomes  converted  into  hydrate  of  lime,  as  also  happens  when  it 
undergoes  the  process  of  slaking.  Lime  may  be  obtained  in  a 
crystalline  state  by  placing  lime-water  under  the  exhausted  re- 
coiverof  an  air-pump,  together  with  sulphuric  acid  in  another  ves- 
sel, the  water  thus  becoming  slowly  evaporated,  imperfect  hexa- 
gonal crystals  will  be  formed,  consisting  of  hydrate  of  lime. 

397.  Calcium  is  capable  of  entering  into  combination  with  oxy- 
gen in  two  proportions,  forming,  besides   lime,  a  peroxide  or 
deutoxide.     The  chloride  of  calcium,  which  is  formed  when  pure 
lime  is  heated  in  chlorine,  is  known  in  commerce  under  the  names 
of  oxyrnuriate  of  lime  and  bleaching  powder,  extensively  used  for 
various  purposes. 

398.  Strontium. — This  metal  may  be  obtained  from  the  earth 
called  strontia,  which  is  an  oxide  of  strontium,  by  a  process 
analogous  to  that  described   for  the  production  of  baryum.     It 
possesses  but  a  moderate  degree  of  lustre,  is  difficult  of  fusion,  and 

What  effect  results  from  the  exposure  of  calcium  to  common  air? 
How  does  that  metal  act  upon  water? 

How  extensive  is  the  protoxide  of  calcium  found  in  nature  ? 
How  may  it  be  obtained  in  a  pure  state  ? 
What  are  its  sensible  properties  ? 
For  what  purpose  is  it  used  In  metallurgy? 

What  remarkable  effect  has  increase  of  temperature  on  water  saturated 
with  lime  ? 
What  use  is  made  of  the  compound  of  lime  with  chlorine  ? 


MAGNESIUM.  151 

not  volatile.  It  is  converted  into  an  oxide  by  exposure  to  atmos- 
pheric air,  and  it  also  decomposes  water.  The  oxide  of  strontium, 
or  strontia,  derives  its  appellation  from  its  having  been  found  in  a 
mineral,  first  discovered  in  a  lead-mine  at  Strontian,  in  Argyll- 
shire, in  which  the  earth  is  combined  with  carbonic  acid.  Strontia 
is  a  gray  pulverulent  mass,  having  decidedly  alkaline  properties. 
It  may  be  slaked  with  water,  giving  out  much  heat,  and  forming 
a  solid  hydrate,  which  is  readily  soluble  in  boiling  water,  and 
deposits  crystals  on  cooling.  When  immersed  in  alcohol,  it  causes 
the  vapours  of  that  fluid  to  burn  with  a  bright  red  flame.  Its  taste 
is  acrid  ;  but  it  differs  from  barytes  in  not  being  poisonous.  Stron- 
tium unites  with  chlorine  and  some  other  bodies;  but  its  com- 
pounds have  been  but  slightly  .examined. 

399.  Magnesium. — Sir  H.  Davy  was  foiled  in  an  attempt  to 
procure  magnesium  by  exposing  the  earth,  in  its  pure  state,  to  the 
action  of  the  Voltaic  battery  ;  but  he  succeeded  better  by  galva- 
nizing solutions  of  the  sulphate  or  nitrate  of  magnesia,  in  contact 
with  mercury      By  this  means  a  metallic  solid   was   obtained, 
which  sunk  rapidly  in  water,  though  surrounded  by  globules  of 
gas,  producing  magnesia;  and  it  quickly  changed  in  air,  becoming 
covered  with  a  white  crust,  or  falling  into  a  fine  powder,  which 
proved  to  be  magnesia.  The  metal  has  since  been  obtained  by  M. 
Bussy  from  the  action  of  potassium  on  chloride  of  magnesium, 
heated  to  redness  in  a  porcelain  tube.     It  appeared  in  the  state  of 
small  brown  scales,  which,  when  rubbed  in  an  agate  mortar,  left  a 
metallic  trace  of  a  leaden  colour.  It  burns,  when  strongly  heated, 
with  a  red  light,  forming  magnesia. 

400.  The  oxide  of  magnesium,  (magnesia,)  in  combination  with 
acids,  is  abundantly  distributed  by  nature  in  the  mineral  kingdom, 
entering  into  the  composition  of  various  rocks,  and  being  found  in 
considerable  quantities  in  the  water  of  the  sea,  and  of  mineral 
springs.      It  usually  occurs  in  the  state  of  sulphate,  from  which 
the  carbonate  is  prepared,  by  the  addition  of  carbonate  of  potash 
or  of  soda,  when  a  precipitation  takes  place.     The  oxide  of  mag- 
nesium may  be  obtained  pure  by  exposing  carbonate  of  magnesia 
to  a  strong  red  heat,  and  the  product,  known  by  the  name  of 
calcined  magnesia,  is  frequently  used  in  medicine.     It  is  a  soft, 
white,  infusible  powder,  having  neither  taste  nor  smell.  It  slightly 
reddens  turmeric,  and  has  some  action  on  the  blue  tint  of  violets, 
turning  it  green,  like  alkalies. 

Magnesium  combines  with  chlorine  and  iodine. 

Whence  was  strontium  first  procured? 

What  are  its  properties  ? 

What  effect  has  this  metal  on  alcohol  ? 

\Vhat  different  methods  have  been  employed  to  obtain  the  metal  mag- 
nesium ? 

To  what  extent  does  the  compound  of  magnesium  and  oxygen  present 
itself  in  nature  ? 

Under  what  name  is  that  compound,  when  pure,  generally  known  ? 

What  alkaline  property  does  it  possess  ? 


1 52  CHEMISTRY. 

401.  Aluminum. — This  metal  has  been  obtained  in  the  state  of 
a  finely-divided,  gray  substance,  or  in  small  scales  with  some 
metallic  lustre.     It  is  very  difficult  of  fusion  ;  and  though  in  the 
pulverulent  state  it  seems  not  to  conduct  electricity,  it  becomes  a 
conductor  when  its  particles  are  united.     It  does  not  become  oxi- 
dized by  mere  exposure  to  the  air;  but  if  heated  almost  to  red- 
ness, it  burns,  forming   a  white  substance,  having  the  general 
properties  of  aluminous  earth. 

402.  The  oxide  of  aluminum  or  alumine,  is  found  in  abundance 
in  the  mineral  kingdom,  constituting,  either  alone  or  with  other 
substances,  most  of  the  precious  stones,  as  the  sapphire,  the  topaz, 
the  ruby,  and  the  garnet ;  and  it  is  a  constituent  part  of  the  hardest 
and  most  ancient  rocks,  and  in  general  also  of  the  superior  soil. 
In  the  state  of  clay  it  is  largely  used  in  making  tobacco-pipes, 
bricks,  pottery,  and  porcelain.  In  combination  with  sulphuric  acid, 
this   oxide  forms  alum,  so  extensively  used  in  the  arts  and  in 
medicine.    Pure  alumine  may  be  obtained  by  precipitating  a  solu- 
tion of  alum  (sulphate  of  alumine)  in  water,  by  means  of  ammonia 
or  carbonate  of  potash.     A  white,  bulky  hydrate  of  alumine  will 
thus  be  obtained,  which,  when  well  washed  and  exposed  to  a 
white  heat,  will  yield  the  earth  in  a  state  of  purity. 

403.  Alumine  is  a  white  bland  powder,  which  adheres  to  the 
tongue,  but  has  neither  taste  nor  smell,  and  does  not  affect  vegeta- 
ble colours.    It  is  insoluble  in  water,  but  when  moistened  with  it, 
forms  a  d  uctile,  cohesive  mass.    It  has  a  great  affinity  for  moisture  ; 
and  after  ignition,  it  will  absorb  from  the  atmosphere  a  quantity 
of  water  equal  to  half  its  weight.  This  earth  enters  into  permanent 
combinations  with  various  animal  and  vegetable  colouring  matters, 
and  hence  it  is  of  great  use  in  dying  and  calico-printing. 

Chloride  of  aluminum  is  a  yellowish,  transparent  crystalline 
substance,  which  rises  in  vapour  at  212°.  When  exposed  to  the 
air  it  rapidly  deliquesces,  forming  an  acid  solution. 

404.  Zirconium. — This  metal  has  been  obtained  from  the  earth 
called  zircon  (oxide  of  zirconium)  by  Galvanism,  and  also  by  heat- 
ing potassium  with  a  peculiar  salt,  fluate  of  zirconia  and  potash 
carefully  dried.  It  is  thus  procured  in  the  state  of  a  black  powder, 
difficultly  soluble  in  acids,  except  the  hydrofluoric,  which  readily 
acts  on  it,  extricating  hydrogen.  When  rubbed  between  two  hard 
substances,  it  appears  in  the  form  of  shining  scales,  of  a  dark 
gray  colour.  If  heated  in  atmospheric  air,  it  burns  brightly,  form- 
ing zircon  earth.     This  earth  (oxide  of  zirconium)  is  a  white 

What  is  the  appearance  of  aluminum  ? 
How  is  it  affected  by  heat  ? 

What  is  the  chemical  nature  of  the  chief  ingredient  of  most  of  the  pre- 
cious stones  ? 

For  what  purposes  in  the  arts  is  alumine  employed  ? 

How  may  it  be  obtained  in  a  pure  state  ? 

What  distinguishing  sensible  properties  does  it  possess  ? 

What  relation  has  pure  alumine  to  water  ? 

How  is  it  employed  in  the  arts  ? 

How  has  zirconium  been  procured  ?    Enumerate  its  several  properties. 


THORINUM.  153 

insipid  powder,  which  forms  salts  with  different  acids,  and  is 
sparingly  dissolved  by  the  carbonated  alkalies ;  but  not  by  the 
alkalies  in  a  pure  state. 

405.  Glucinum. — This  metal  may  be  obtained  by  decomposing 
its  chloride  by  potassium.  It  is  a  gray  substance,  having  but  lit- 
tle metallic  lustre,  and  very  difficult  of  fusion.  It  is  not  affected 
by  air  or  water  at  common  temperatures ;  but  when  heated,  it 
burns,  forming  glucina,  or  oxide  of  glucinum.  This  oxide  was 
first  discovered  in  the  beryl,  and  it  also  occurs  in  the  emerald  of 
Peru,  and  in  the  euclase  ;  but  has  not  yet  been  found  in  any  other 
minerals.  It  is  a  fine,  white,  soft  powder,  adhering  to  the  tongue 
like  pure  clay.  It  does  not  affect  vegetable  colours,  and  is  insolu- 
ble in  water;  with  which,  however,  it  forms  a  ductile  paste. 
With  the  acids  it  combines  to  form  salts,  having  a  sweetish, 
astringent  taste  ;  whence  its  name.* 

406  Yttrium. — This  is  the  metallic  basis  of  the  earth  called 
.  yttria  or  ittria,  which  was  discovered  in  a  mineral  found  in  the 
quarry  of  Ytterby  in  Sweden.  This  earth  has  since  been  met  with 
only  in  one  other  mineral  in  the  same  country.  Yttria  (oxide  of 
yttrium)  is  an  insipid,  white  powder,  which  has  no  action  on 
vegetable  colours,  and  is  remarkable  for  its  specific  gravity,  which 
is  4.8.  It  is  insoluble  in  water,  and  incapable  of  fusion,  except  at 
a  very  intense  heat.  With  the  acids  it  forms  salts,  having  a 
sweetish,  austere  taste,  but  which  have  hitherto  been  but  slightly 
examined.  The  metal  has  been  procured,  by  decomposing  the 
chloride  of  yttrium  by  means  of  potassium,  in  the  state  of  iron- 
gray  scales,  which  burn  brilliantly  when  heated  in  oxygen  gas  or 
common  air,  forming  yttria.  The  metal  is  not  acted  on  by  water, 
but  dissolves  in  sulphuric  acid. 

407.  Thorinum. — Thorinum,  or  thorium,  is  the  name  given  to 
a  metal  discovered  by  Berzelius.  In  1816,  in  analysing  some 
Swedish  minerals,  he  obtained  an  earthy  substance,  which  he 
concluded  to  be  the  oxide  of  a  new  metal,  (thorium,)  but  he 
subsequently  found  it  to  be  a  subphosphate  of  yttria.  However, 
in  1828,  Berzelius  received  a  black,  heavy  mineral,  from  the 
vicinity  of  Brevig,  in  Norway,  which,  on  analysis,  was  found  to 
consist  chiefly  of  a  silicate  of  a  new  earth,  which  constituted  about 
58  per  cent,  of  the  whole  mineral.  To  the  base  of  this  earth  he 
gave  the  name  of  thorium,  because  it  resembled  in  its  properties 
the  subphosphate  of  yttria,  to  which  the  name  had  been  previously 
applied.  Thoria  (oxide  of  thorium)  displays  considerable  analo- 
gies with  yttria,  zirconia,  and  glucina. 

In  what  state  was  the  oxide  of  glucinum  first  discovered  ? 

What  peculiar  properties  have  its  compounds  with  acids? 

Whence  was  yttria  first  procured  ? 

By  what  means  is  its  metallic  base  separated  from  composition? 

With  what  solvent  will  the  metal  combine  ? 

To  what  substance  was  the  name  thorium  first  given  ? 

To  what  has  it  been  subsequently  applied  ? 

*  From  the  Greek  word  TAvKv?,  sweet. 


154  CHEMISTRY. 

408.    Binary  Combinations  of  the  Metallic  Elements  of  the  Third 
Class  with  Oxygen  and  some  other  Non-metallic  Elements. 

Iron. 

Black  oxide  of  I.,  1  Ir.  1  Ox. 
Red  oxide  of  I.,  2  Ir.  3  Ox. 
Chloride  of  I.,  1  Ir.  1  Ch. 
Pefchloride  of  I.,  2  Ir.  3  Ch. 
Sulphuret  of  I.,  1  Ir.  1  S. 
Bisulphuret  of  I.,  1  Ir.  2  S. 

Nickel. 

Oxide  of  N.,  1  Nk.  1  Ox. 
Peroxide  of  N.,  2  Nk.,  3  Ox. 
Sulphuret  of  N.,  1  Nk.  1  S. 

Zinc. 

White  oxide  of  Z.,  1  Zn.  1  Ox. 
Chloride  of  Z.,  1  Zn.  1  Ch. 
Sulphuret  of  Z.,  (blende,)  1  Zn.  1  S. 

Cadmium. 

Oxide  of  C.,  1  Cad.  1  Ox. 
Sulphuret  of  C.,  1  Cad.  1  S. 

Cerium. 

Oxide  of  C.,  1  Cer.  1  Ox. 
Peroxide  of  C.,  2  Cer.  3  Ox. 

Lead. 

Protoxide  of  L.,  1  Ld.  1  Ox. 
Red  oxide  of  L.,  (minium,)  2  Ld.  3  Ox. 
Brown  oxide  of  L.,  1  Ld.  2  Ox. 
Chloride  of  L.,  1  Ld.  1  Ch. 
Sulphuret  of  L.,  (galena,)  1  Ld.  1  S. 

Copper. 

Oxidule  of  C.,  2  Cop.  1  Ox. 
Oxide  of  C.,  1  Cop.  1  Ox. 
Deutoxide  of  C.,  1  Cop.  2  Ox. 
Chloride  of  C. 
Perchloride  of  C. 
Hemisulphuret  of  C.,  2  Cop.  1  S. 
Sulphuret  of  C.,  1  Cop.  1  S. 

Enumerate  the  metallic  elements  of  the  third  class. 
What  are  the  binary  compounds  of  iron? — of  nickel? — of  zinc? — of  cad 
mium  ? — of  cerium  ? — of  lead  ? — of  copper  ? 


METALLIC  ELEMENTS.  155 

Copper  continued. 


Cop.  2  S. 


Cop.  5  S. 
Phosphuret  of  C.,  1  Cop.  1  Ph. 

Bismuth. 

Oxide  of  B.,  1  Bis.  1  Ox. 
Chloride  of  B.,  1  Bis.  1  Ch. 
Sulphuret  of  B.,  1  Bis.  1  S. 

Mercury. 

Black  oxide  of  M.,  1  Her.  1  Ox. 
Red  oxide  of  M.,  1  Mer.  2  Ox. 
Chloride  of  M.,  (calomel,)  1  Mer.  1  Ch. 
Perchloride  of  M.  (corrosive  sublimate,)  1  Mer.  2  Ch. 
Sulphuret  of  M.,  (Ethiops  mineral,)  1  Mer.  1  S. 
Bisulphuret  of  M.,  (vermilion,)  1  Mer.  2  S. 

Silver. 

Oxide  of  S.,  1  Sil.  1  Ox. 

Chloride  of  S.,  (luna  corena,  horn  silver,)  1  Sil.  1  Ch. 

Sulphuret  of  S.,  1  Sil.  1  S. 

Gold. 

Oxide  of  G.,  1  Gd.  1  Ox. 
Peroxide  of  G.,  1  Gd.  3  Ox. 
Chloride  of  G.,  1  Gd.  1  Ch. 
Perchloride  of  G.,  1  Gd.  3  Ch. 
Sulphuret  of  G.,  1  Gd.  1  S. 
Persulphuret  of  G.,  1  Gd.  3  S. 

Platina. 

Oxide  of  P.,  1  PI.  1  Ox. 
Deutoxide  of  P.,  1  PI.  2  Ox. 
Chloride  of  P.,  1  PI.  1  Ch. 
Bichloride  of  P.,  1  PI.  2  Ch. 

Palladium. 

Oxide  of  P.,  1  Pal.  1  Ox. 
Sulphuret  of  P.,  1  Pal.  1  S. 

How  many  persulphurets  does  copper  form  ? 

What  are  the  binary  compounds  of  bismuth?  —  of  mercury  ?—  of  silver  ?- 
of  gold  ? 

With  which  of  the  non-metallic  elements  does  platina  combine  ? 
With  what  ones  does  palladium  unite  ? 


156  CHEMISTRY. 

Rhodium. 

Oxide  of  R.,  1  Rh.  1  Ox. 
Peroxide  of  R.,  2  Rh.,  3  Ox. 

Iridium. 

Irid.  1  Ox. 

Oxide,  of 

1  Irid.  3  Ox. 
Osmium. 

ri  os.  i  ox. 

2  Os.  3  Ox. 
Oxides  of  O.J  1  Os.  2  Ox. 

1  Os.  3  Ox. 
.1  Os.  4  Ox. 

409.  Iron.  But  few  of  the  elementary  bodies  with  which  we  are 
acquainted  occur  so  abundantly  and  in  so  many  various  forms  as 
iron.     Among  the  metals,  excepting  some  of  the  bases  of  earths 
and  alkalies,  there  is  not  one  which  enters  so  largely  into  the  com- 
position of  mineral,  vegetable,  and  animal  substances.     It  is  also 
distinguished   for   its   general  utilty,  possessing  admirable  pro- 
perties, adapting  it  for  the  construction  of  a  multiplicity  of  weapons 
and  instruments,  useful  in  peace  and  war,  in  arts,  manufactures, 
and  for  domestic  purposes.    Its  capabilities  were  known,  and,  to  a 
certain  extent,  duly  appreciated  by  the  ancients ;  but  they  have 
been,  in  modern  times,  far  more  fully  developed,  and  the  metal 
and  its  compounds  consequently  rendered  subservient  in  a  most 
extraordinary  degree  to  the  luxuries  as  well  as  the  wants  of  our 
contemporaries.      Chain-bridges,   steam-engines,  watch-springs, 
and  magnets,  are  among  the  numerous  articles  constructed  of  this 
metal,  the  invention  of  which  is  comparatively  of  modern  date. 

410.  Though  iron,  when  pure,  requires,  to  melt  it,  an  extremely 
high  temperature,  it  is  susceptible  of  an  imperfect  kind  of  fusion 
at  a  white  heat;  for  when  exposed  to  that  heat, it  becomes  so 
much  softened,  especially  at  the  surface,  that  if  two  pieces  are 
placed  in  contact,  and  hammered,  they  may  be  most  firmly  and 
securely  united.     This  operation  is  termed  welding,  and  the  tem- 

iture  at  which  it  is  effected,  is  sometimes  called  a  welding 


411.  The  combustibility  of  iron  has   been  already  noticed.* 

With  which  of  the  non-metallic  elements  does  rhodium  combine? — iri- 
dium  ? — osmium  ? 

Which  of  the  metals  is  the  most  widely  diffused  ? 
Into  what  classes  of  natural  productions  does  iron  enter  ? 
How  early  did  mankind  employ  it  for  useful  purposes  ? 
To  what  purpose  is  the  semi-fluid  state  of  iron  applied  ? 
What  is  meant  by  welding  ? 

*  See  Nos.  171,  172. 


NICKEL ZINC CADMIUM.  157 

When  it  is  burnt,  either  in  oxygen  gas  or  atmospheric  air,  the 
protoxide  of  iron  is  formed  ;  if  this  compound  be  exposed  to  a  red 
heat  for  some  hours,  it  combines  with  an  additional  quantity  of 
oxygen,  and  becomes  converted  into  the  peroxide.  Both  the 
oxides  combine  with  water,  constituting  hydrated  oxides  of  iron. 
Chloride  of  iron  is  a  brittle,  lameller  substance,  of  a  gray  colour, 
which  requires  for  its  fusion  a  red  heat.  Perchlcride  of  iron  is  the 
product  of  the  combustion  of  iron  wire  in  chlorine  gas.  The 
metal  burns  with  a  red  light,  forming  a  compound  which  sublimes 
in  iridescent  brown  scales.  The  bisulphurut  of  iron  is  a  native 
mineral,  occurring  in  the  state  of  gold-coloured  crystals,  called 
pyrites.  Iron  combines  in  variable  proportions  with  carbon : 
when  the  metal  is  in  excess,  composing  the  different  kinds  of 
steel  and  cast-iron ;  and  when  the  carbon  largely  exceeds,  form- 
ing plumbago. 

412.  Nickel. — This  is  a  hard  metal,  of  a  white  colour,  malleable 
and  ductile,  but  difficult  of  fusion,  and  not  acted  on  by  atmospheric 
air  or  water  at  common  temperatures.     When  pure  it  may  be 
rendered  magnetic,  like  iron  ;  and  it  has  heretofore  been  sometimes 
employed  in  the  construction  of  magnetic  needles.     If  exposed  to 
intense  heat  with  access  of  air,  it  becomes  slowly  oxidized ;  and 
it  burns  with  vivid  scintillations  in  oxygen  gas. 

413.  Zinc, — This  metal  in  appearance  resembles  lead,  but  is, 
when  untarnished,  of  a  lighter  colour.  It  speedily  attracts  oxygen 
when  exposed  to  air  and  moisture;  and  it  is  easily  dissolved  by 
acids  and  alkalies, -both  in  the  metallic  state  and  when  oxidated. 
It  is  malleable  and  ductile  when  heated  to  between  210°  and  300° 
Fahrenheit.     At  about  725°*  it  melts,  and  becomes  cyrstallized 
on  cooling.     If  exposed  to  a  temperature  beyond  its  melting-point, 
with  the  access  of  air,  it  burns  with  a  bright,  bluish  flame,  form- 
ing the  oxide,  formerly  called  flowers  of  zinc. 

414.  Cadmium  resembles  tin   in  its  sensible  properties;  and 
when  heated  in  atmospheric  air  forms  a  sublimate,  which  condenses 
into  a  brownish-yellow  oxide.     The  oxides  of  this  as  well  as  the 
three  preceding  metals,  are  readily  reduced  by  heat  alone  to  the 
metallic  state. 

415.  Cerium. — The  protoxide  of  cerium  is   a  white  powder, 
which  differs  from  the  oxides  of  the  metals  just  described,  in  being 

What  two  compounds  does  it  form  with  oxygen  ? 
vWhat  is  the  appearance  of  chloride  of  iron? 
To  what  is  the  term  pyrites  applied  ? 
What  are  the  chief  properties  of  nickel  ? 
What  property  has  it  in  common  with  iron? 
Between  what  temperatures  is  zinc  malleable  ? 
About  what  temperatures  is  that  metal  said  to  melt  ? 
To  which  of  the  other  metals  is  cadmium  most  nearly  allied  ? 
By  what  means  are  the  oxides  of  iron,  nickel,  zinc,  and  cadmium  re- 
duced to  the  metallic  state? 

*  658  according  to  Daniell. 

o 


158  CHEMISTRY. 

extremely  difficult  of  reduction.  The  metal  itself  is  but  imperfectly 
known. 

416.  Lead. — This  is  well  known  to  be  a  heavy,  soft,  and  readily 
fusible  metal,  which,  though  malleable  and  ductile,  is  deficient  in 
tenacity.  It  soon  becomes  oxidized  when  exposed  to  a  moist  at- 
mosphere. When  heated  by  means  of  an  oxyhydrogen  blowpipe, 
it  burns  with  a  bluish  flame.  If  melted  and  kept  stirred,  so  as  to 
promote  the  free  access  of  air,  it  becomes  converted  into  the  pro- 
toxide, a  yellow  powder,  used  as  a  pigment  under  the  name  of 
massicot;  and  in  a  semi-vitrified  state  it  constitutes  litharge.  The 
brown  oxide  of  lead  exhibits  the  phenomenon  of  spontaneous  com- 
bustion, when  it  is  triturated  with  sulphur.  Lead  in  a  finely- 
divided  state,  if  thrown  into  chlorine  gas  moderately  warmed, 
burns  with  a  white  flame,  and  throws  off  sparks.  The  product  of 
this  operation  is  chloride  of  lead,  which  may  also  be  obtained  by 
decomposing  the  solution  of  lead  in  nitric  acid,  by  means  of  chlo- 
ride of  sodium,  (common  salt.)  It  fuses  at  a  heat  below  redness, 
and  when  cooled  again,  has  the  appearance  of  a  horny  substance, 
whence  it  was  formerly  named  horn  lead,  (plumbum  curneum.) 

417.  Copper. — This  metal  being  used  for  many  domestic  purposes, 
its  physical  properties  are  generally  known.     It  is  malleable  and 
ductile  beyond  most  other  metals,  except  gold,  silver,  platina,  and 
iron ;    and  hence  it  forms  fine  wire,  and  may  be  beaten  into  thin 
leaves.      It  burns  brilliantly  when  heated  in  the  combined  flame 
of  oxygen  and  hydrogen,  giving  out  a  dazzling  green  light.  If  ex- 
posed to  air  and  moisture,  it  tarnishes,  combining  with  oxygen  to 
form  a  bluish-green  rust,  (serugo.}    The  deutoxide  or  peroxide  of 
copper  is  an  insipid,  black  powder.     Leaves  or  filings  of  copper 
take  fire,  and    burn  spontaneously  in  chlorine  gas,  forming  the 
chloride  of  copper,  a  yellowish,  slightly  transparent  substance, 
easily  fusible,  which  has  been  called  resin  of  copper.     If  sulphur 
and  filings  of  copper  be  heated  together,  a  sudden  and  brilliant 
combustion  takes  place,  even  when  the  process  is  conducted  in  a 
vacuum.* 

418.  Bismuth. — This  is  a  light  reddish-coloured  metal,  of  a 
lamellar  structure,  moderately  hard,  and  destitute  of  malleability. 
It  becomes  tarnished  by  exposure  to  air ;  but  is  not  affected  by 
water.  Its  fusibility  has  been  already  noticed.    If  strongly  heated 
in  the  air,  it  burns  with  a  blue  flame,  forming  a  yellowish  oxide, 
which  has  been  called  flowers  of  bismuth.     This  substance,  like 
the  oxide  of  lead,  is  fusible  and  verifiable.  Finely-divided  bismuth 
becomes  inflamed  when  gently  heated  in  chlorine  gas,  forming  a 
gray,  granular  compound. 

What  are  the  chemical  properties  of  lead  ? 

What  is  the  colour  of  the  flame  of  copper  in  oxygen  ? 

What  effect  has  chlorine  on  copper  ? 

What  takes  place  when  copper  in  fine  particles  is  heated  with  sulphur  ? 

What  are  the  colour  and  crystalline  form  of  bismuth  ? 

3y  what  means  may  the  combustion  of  bismutli  be  effected  ? 

See  No.  70. 


MERCURY SILVER GOLD.  159 

419.  Mercury. — This  metal  is  distinguished  by  its  extraordinary 
fusibility,  so  that  it  requires  a  temperature  39°  below  zero,  Fahren- 
heit, to  congeal  or  render  it  solid.    It  is  in  that  state  malleable  and 
ductile,  though  not  to  any  great  extent.     It  is  extremely  volatile, 
subliming-  in  some  degree  at  low  temperatures  ;  and  at  about  660° 
it  boils  rapidly,  and  may  thus  be  purified   by  distillation,  like 
water.     When,  heated  a  little  beyond  the  boiling  point,  it  becomes 
oxidated ;  and  if  the  oxide  be  exposed  to  a  considerably  higher 
temperature,  the  oxygen  is  driven  off,  and  the  metal  revived.* 

420.  The  chlorides  of  mercury  are  among  the  most  important 
preparations  of  this  metal  used  in  medicine.    The  first,  commonly 
called  calomel,  may  be  formed  by  exposing  the  metal  to  chlorine 
gas  at  common  temperatures ;  but  the  usual  mode  of  obtaining 
this  compound  is  by  decomposing  the  solution  of  mercury  in  nitric 
acid,  by  means  of  muriatic  acid  or  chloride  of  sodium,  (common 
salt.)     The  product  is  a  ponderous  white  powder,  which,  when 
exposed  to  heat,  sublimes  unaltered.    The  perchloride  of  mercury 
is  a  crystalline  substance,  which  may  be  procured  by  heating  the 
metal  in  chlorine  gas ;  but  it  is  prepared  for  use  by  boiling  together 
sulphate  of  mercury  and  common  salt.     It  is  well  known  as  a 
powerful  poison,  under  the  name  of  corrosive  sublimate.     The  bi- 
sulphuret  of  mercury,  which  occurs  as  a  native  mineral,  under  the 
name  of  cinnabar,  and  the  same  substance  artificially  produced,  af- 
fords a  fine  scarlet  colour  for  painting. 

421.  Silver. — This  metal  requires  a  great  heat  to  melt  it ;  but  by 
a  fierce  and  long  continued  fire  it  may  be  volatilized.  It  does  not 
tarnish  in  the  air  from  absorption  of  oxygen  ;  but,  when  sulphurous 
vapours  are  present,  its  surface  becomes  tinged  with  purple  from 
the  formation  of  sulphuret  of  silver ;  and  the  same  effect  is  produced 
when  a  silver  spoon  is  dipped  in  the  yolk  of  an  egg,  which  con- 
tains sulphur.  The  oxide  of  silver  may  be  formed  by  exposing  the 
metal  to  intense  heat,  with  the  access  of  air ;  but  it  is  more  readily 
obtained  by  decomposing  the  nitrate  of  silver  with  lime  water, 
when  it  constitutes  a  tasteless  olive-coloured  powder,  insoluble 
in  water.  Chloride  of  silver  has  the  same  horny  appearance  as  chlo- 
ride of  lead;  and  it  is  therefore  called  horn  silver,  (luna  cornea.} 

422.  Gold. — The  most  powerful  heat  of  our  furnaces  has  no  ef- 
fect on  this  metal  beyond  that  of  fusing  it ;  but  it  may  be  made  to 
undergo  combustion,  and  form  a  purple  oxide,  by  heating  it  with 
the  flame  of  an  oxy  hydrogen  blowpipe,  or  by  means  of  electricity 

What  remarkable  property  distinguishes  mercury  from  all  other  metals  ? 

What  class  of  the  compounds  of  this  metal  are  used  in  medicine  ? 

What  is  the  form  of  corrosive  sublimate  and  what  is  the  common  process 
of  procuring  it  ? 

To  what  purpose  is  the  bisulphuret  of  mercury  applied  ? 

What  chemical  properties  of  silver  can  you  enumerate? 

What  causes  the  colour  given  to  a  silver  spoon  by  dipping  it  in  the  yolk 
of  an  egg  ? 

How  may  gold  be  oxidized  ? 

*  See  No.  82. 


160  CHEMISTRY. 

It  may  also  be  oxidated  indirectly  by  solution  in  the  nitro-muriatic 
acid,  (aqua  regie,}  and  precipitation  by  caustic  potash  or  magnesia. 
If  the  peroxide  of  gold  be  dissolved  in  muriatic  acid,  and  ammonia 
be  employed  to  precipitate  it,  a  detonating  powder  (Jlurum  Ful- 
minans)  will  be  obtained,  which  explodes  when  rubbed  or  heated 

423.  Platina. — This  metal  in  a  state  of  purity  is  the  heaviest 
body  hitherto  discovered,  having  nearly  22  times  the  specific  gra- 
vity of  water.     It  is  so  difficult  of  fusion,  that  it  can  only  be  pre- 
pared for  use  by  a  complicated  process.    But,  like  iron,  it  may  be 
welded  by  hammering  the  metal  when  intensely  heated  ;  and  thus 
vessels  and  other  utensils  may  be  formed,  highly  valuable  for  the 
purposes  of  art,  on  account  of  their  relative  indestructibility.    Pla- 
tina may  be  oxidated  by  treating  it  with  nitro-muriatic  acid  and 
alkali,  as  in  the  case  of  gold,  or  by  heating  it  with  nitre,  and 
likewise  by  the  influence  of  electricity. 

424.  Palladium,  lihodium,  In'dium,  and    Osmium  are  metals 
which  have  been  found  in  comparatively  small  quantities,  mixed 
with  crude  platina,  in  the  state  in  which  it  appears  in  commerce. 
Palladium  forms  a  hard,  durable  alloy  with  gold,  which  has  been 
used  in  the  construction  of  mathematical  instruments  :  and  rhodium 
has  been  employed  for  pointing  the  nibs  of  pens.  Iridium  and  os- 
mium do  not  appear  to  have  been  applied  to  any  useful  purpose; 
nor  do  the  compounds  of  either  of  these  four  metals  require  to  be 
further  noticed. 

425.  Such  is  an  outline  of  the  character  and  composition  of  the 
various  simple  ingredients  of  which  the  material  world  around  us 
is  composed.     It  can  hardly  be  expected  that  we  should,  in  a 
treatise  like  this,  enter  into  an  elaborate  statement  of  all  the 
various  forms  which  they  present  when  combined.     It  will,  be- 
sides, be  in  course  to  state,  when  treating  of  mining,  of  the  methods 
of  ascertaining  the  chemical  nature  of  ores — and,  under  the  head 
of  mineralogy,  we  shall  give  some  brief  views  of  the  general  con- 
stituents of  mineral  substances.     But  it  will  be  proper  here  to 
exhibit  an  application  of  the  principles  of  chemistry  to  certain 
other  important  subjects  of  which  this  science  is  justly  regarded 
as  an  indispensable  groundwork.     These  are  the  chemical  com- 
binations found  in  the  vegetable  and  animal  kingdoms,  considered 
as  separate  departments  of  natural  history,  the  nature  of  soils  and 
the  character  of  mineral  wraters.     Previously  to  the  consideration 
of  these  topics,  it  will  be  proper  for  us  to  explain  some  of  the 
methods  of  analysis. 

Analysis. 

426.    This  word  is  applied  by  chemists  to  denote  that   se- 
ries of  operations  by  which  the  component  parts  of  bodies  are 

How  is  fulminating  gold  procured  ? 

What  is  the  relative  weight  of  platina  compared  with  other  metals  ? 
What  mechanical  processes  may  be  performed  on  platina  at  a  high  tem- 
perature ?     How  may  it  be  combined  with  oxygen  ? 
What  use  has  been  made  of  the  metal  palladium  ? 


ANALYSIS  OF  EARTHS  AND  STONES.  161 

determined,  whether  they  be  merely  separated,  or  exhibited  apart 
from  each  other ;  or  whether  these  distinctive  properties  be  exhi- 
bited by  causing  them  to  enter  into  new  combinations. 

Analysis  of  Earths  and  Stones. 

427.  The  first  step  in  the  examination  of  indurated  earths  or 
stones,  is  somewhat  different  from  that  of  such  as  are  pulverulent. 
Their  specific  gravity  should  first  be  examined  ;  also  their  hard- 
ness, whether  they  will  strike  fire  with  steel  or  can  be  scratched 
by  the  nail,  or  only  by  crystal,  or  stones  of  still  greater  hardness  ; 
also  their  texture,   perviousness  to  light,  and  whether  they  be 
manifestly  homogeneous  or  compound  species,  &c. 

428.  (2cf.)  In  some  cases  we  should  try  whether  they  imbibe 
water,  or  whether  water  can  extract  any  thing  from  them  by  ebul- 
lition or  digestion. 

(3c?.)  Whether  they  be  soluble  in,  or  effervesce  with  acids,  be- 
fore or  after  pulverization ;  or  whether  decomposable  by  boiling 
in  a  strong  solution  of  potash,  &c.  as  gypsums  and  ponderous 
spars  are. 

(4/A.)  Whether  they  detonate  with  nitre. 

(5M.)  Whether  they  yield  the  fluoric  acid  by  distillation  with 
sulphuric  acid  or  ammonia,  by  distilling  them  with  potash. 

(6//J.)  Whether  they  be  fusible  per  se  with  a  blowpipe,  and  how 
they  are  affected  by  soda,  borax,  and  microcosmic  salt ;  and 
whether  they  decrepitate  when  gradually  heated. 

(7£A.)  Stones  that  melt  per  se  with  the  blowpipe  are  certainly 
compound,  and  contain  at  least  three  species  of  earth,  of  which 
the  calcareous  is  probably  one;  and  if  they  give  fire  with  steel, 
the  sileceous  is  probably  another. 

429.  Of  the  primary  earths,  only  four  are  usually  met  with  in 
minerals,  viz.  silica,  alumina,  magnesia,  and  lime,  associated  with 
some   metallic   oxides,  which  are   commonly  iron,   manganese, 
nickel,  copper,  and  chromium. 

430.  If  neither  acid  qgp-  alkali  be  expected  to  be  present,  the 
mineral  is  mixed  in  a  silver  crucible,  with  thrice  its  weight  of 
pure  potash  and  a  little  water.     Heat  is  gradually  applied  to  the 
covered  crucible,  and  is  finally  raised  to  redness ;  at  which  tem- 
perature it  ought  to  be  maintained  for  an  hour.     If  the  mass,  on 
inspection,  be  a  perfect  glass,  silica  may  be  regarded  as  the  chief 
constituent  of  the  stone  ;  but  if  the  vitrification  be  very  imperfect, 
and  the  bulk  much  increased,  alumina  may  be  supposed  to  predo- 
minate.    A  brownish  or  dull  green  colour  indicates  the  presence 
of  iron;  a  bright  grass-green,  which  is  imparted  to  water,  that  of 

How  is  the  term  analysis  applied  by  chemists  ? 
What  is  the  first  step  in  the  examination  of  stones  or  earths  ? 
What  are  the  several  processes  after  the  gravity  and  hardness  oi   a  mi- 
neral have  been  ascertained. 

How  many  of  the  primary  earths  usually  occur  in  minerals  ? 
In  what  manner  are  minerals  destitute  of  acids  and  alkalies  to  be  treated  ? 
How  is  the  presence  of  silica  indicated  in  the  course  of  an  analysis  ? 

0  2 


163  CHEMISTRY. 

manganese ;  and  from  a  greenish-yellow,  chromium  may  be  ex- 
pected. The  crucible,  still  a  little  hot,  being  first  wiped,  is  put 
into  a  capsule  of  porcelain  or  platinum ;  when  warm  distilled 
water  is  poured  upon  the  alkaline  earthy  mass,  to  detach  it  from 
the  crucible.  Having  transferred  the  whole  of  it  into  the  capsule, 
muriatic  acid  is  poured  on,  and  a  gentle  heat  applied,  if  necessary, 
to  accomplish  its  solution.  If  the  liquid  be  of  an  orange-red 
•colour,  we  infer  the  presence  of  iron ;  if  of  a  golden-yellow,  that 
of  chromium  ;  and  if  of  a  purplish-red,  that  of  manganese. 

431.  The  solution  is  next  to  be  evaporated  to  dryness  on  a  sand 
bath,  or  over  a  lamp,  taking  care  so  to  regulate  the  heat  that  no 
particles  be  thrown  out.     Towards  the  end  of  the  evaporation,  it 
assumes  a  gelatinous  consistence.     At  this  period  it  must  be 
stirred  frequently  with  a  platinum  spatula  or  glass  rod,  to  promote 
the  disengagement  of  the  muriatic  acid  gas.     After  this,  the  heat 
may  be  raised  to  fully  212°  F.  for  a  few  minutes. 

432.  Hot  water  is  now  to  be  poured  on  in  considerable  abun- 
dance, which  dissolves  every  thing  except  the  silica.     By  filtra- 
tion, this  earth  is  separated  from  the  liquid ;   and  being  washed 
with  hot  water,  it  is  then  dried,  ignited,  and  weighed.     It  consti- 
tutes a  fine  white  powder,  insoluble  in  acids,  and  feeling  gritty 
between  the  teeth.     If  it  be  coloured,  a  little  dilute  muriatic  acid 
must  be  digested  on  it,  to  remove  the  adhering  metallic  particles, 
which  must  be  added  to  the  first  solution.     This  must  now  be  re- 
duced by  evaporation  to  the  bulk  of  half  a  pint.     Carbonate  of 
potash  being  then  added  till  it  indicates  alkaline  excess,  the  liquid 
must  be  made  to  boil  for  a  little.     A  copious  precipitation  of  the 
earth  and  oxide  is  thus  produced.     The  whole  is  thrown  on  a 
filter,  and  after  it  is  so  drained  as  to  assume  a  semi-solid  consist- 
ence, it  is  removed  by  a  platinum  blade,  and  boiled  in  a  capsule 
for  some  time,  with  solution  of  pure  potash.     Alumina  and  glu- 
cina  are  thus  dissolved,  while  the  other  earths  and  the  metallic 
oxides  remain. 

433.  This  alkalino-earthy  solution,  separated  from  the  rest  by 
filtration,  is  to  be  treated  with  an  excels  of  muriatic  acid ;  after 
which  carbonate  of  ammonia  being  added  also  in  excess,  the 
alumina  is  thrown  down,  while  the  glucina  continues  dissolved. 
The  first  earth  separated  by  filtration,  washed,  dried,  and  ignited, 
gives  the  quantity  of  alumina.    The  nature  of  this  may  be  further 
demonstrated,  by  treating  it  with  dilute  sulphuric  acid  and  sul- 
phate of  potash,  both  in  equivalent  quantities,  when  the  whole 
will  be  converted  into  alum.     The  filtered  liquid  will  deposit  its 
glucina,  on  dissipating  the  ammonia  by  ebullition.     It  is  to  be 
separated  by  filtration,  to  be  washed,  ignited,  and  weighed. 

434.  The  mingled  metallic  oxides  must  be  digested  with  abun- 
dance of  nitric  acid,  to  acidify  the  chromium.     The  liquid  is  next 
treated  with  potash,  which  forms  a  soluble  chromate,  while  it 

How  is  the  presence  of  iron  inferred  ? 

How  are  earthy  materials  separated  from  the  solution  of  a  mineral  ? 


ANALYSIS  OF  EARTHS  AND  STOXES.  163 


lickel  is  separated  from  the  iron,  by  treating-  their  solution  in 
nuriatic  acid  with  water  of  ammonia.     The  latter  oxide,  which 


throws  down  the  iron  and  nickel.  The  chromic  acid  may  be  se- 
parated from  the  potash  by  muriatic  acid  and  digestion  with  heat, 
washed,  dried  till  it  becomes  a  green  oxide,  and  weighed.  The 
nickel 
muriatic 

falls,  may  he  separated  by  the  filter,  dried,  and  weighed.  By 
evaporating  the  liquid,  and  exposing  the  dry  residue  to  a  moderate 
heat,  the  ammoniacal  salt  will  sublime,  and  leave  the  oxide  of 
nickel  behind.  The  whole  separate  weights  must  now  be  col- 
lected in  one  amount,  and  if  they  constitute  a  sum  within  two  per 
cent,  of  the  primitive  weight,  the  analysis  may  be  regarded  as 
giving  a  satisfactory  account  of  the  composition  of  the  mineral. 
But  if  the  deficiency  be  considerable,  then  some  volatile  ingre- 
dient, or  some  alkali  or  alkaline  salt,  may  be  suspected. 

435.  A  portion  of  the  mineral,  broken  into  small  fragments, 
is  to  be  ignited  in  a  porcelain  retort,  to  which  a  refrigerated  re- 
ceiver is  fitted.     The  water,  or  other  volatile  or  condensable  mat- 
ter, if  any  be  present,  will  thus  be  obtained.     But  if  no  loss  of 
weight  be  sustained  by  ignition,  alkali,  or  a  volatile  acid,  may  be 
looked  for.    The  latter  is  usually  the  fluoric.    It  may  be  expelled 
by  digestion  with  sulphuric  acid.     It  is  exactly  characterized  by 
its  property  of  corroding  glass. 

436.  Beside  this  general  method,  some  others  may  be  used  in 
particular  cases.    Thus,  to  discover  a  small  proportion  of  alumina 
or  magnesia  in  a  solution  of  a  large  quantity  of  lime,  pure  ammo- 
nia may  be  applied,  which  will  precipitate  the  alumina  or  magne- 
sia, (if  any  there  be.)  but  not  the  lime.    Distilled  vinegar  applied 
to  the  precipitate  will  discover  whether  it  be  alumina  or  magnesia. 

437.  (Zdly.}  A  minute  portion  of  lime  or  baryta,  in  a  solution 
of  alumina  or  magnesia,  may  be  discovered  by  the  sulphuric  acid, 
which  precipitates  the  lime  and  baryta :  the  solution  should  be 
dilute,  else  the  alumina  also  would  be  precipitated.     If  there  be 
not  an  excess  of  acid,  the  oxalic  acid  is  still  a  nicer  test  of  lime. 

438.  (3c?/y.)  A  minute  proportion  of  alumina  in  a  large  quantity 
of  magnesia  may  be  discovered,  either  by  precipitating  the  whole 
and  treating  it  with  distilled  vinegar ;  or  by  heating  the  solution 
nearly  to  ebullition,  and  adding  more  carbonate  of  magnesia  until 
the  solution  is  perfectly  neutral,  which  it  never  is  when  alumina 
is  contained  in  it,  as  this  requires  an  excess  of  acid  to  keep  it  in 
solution. 

439.  (4M/y.)  A  minute  portion  of  magnesia  in  a  large  quan- 
tity of  alumina,  is  best  separated  by  precipitating  the  whole,  and 
treating  the  precipitate  with  distilled  vinegar. 

How  are  nickel  and  iron  separated  ? 

How  is  the  presence  of  fluoric  acid  detected  in  the  course  of  an  analysis? 

What  test  detects  the  presence  of  alumina  or  magnesia  in  a  large  quan- 
tity of  lime  ? 

How  is  a  small  proportion  of  alumina  known  to  exist  in  a  large  quan- 
tity of  magnesia  ? 


164  CHEMISTRY. 

440.  (Lastly.}  Lime  and  baryta  are  separated  by  precipitating 
both  with  the  sulphuric  acid,  and  evaporating  the  solution  to  a  small 
compass,  pouring  off  the  liquor,  and  treating  the  dried  precipitate 
with  500  times  its  weight  of  boiling  water :  what  remains  undis- 
solved  is  sulphate  of  baryta. 

441.  Sir  H.  Davy  observes,  that  boracic  acid  is  very  useful  in 
analyzing  stones  that  contain  a  fixed  alkali ;  as  its  attraction  for 
the  different  earths  at  the  heat  of  ignition  is  considerable,  and  the 
compounds  it  forms  with  them  are  easily  decomposed  by  the 
mineral  acids  dissolved  in  water.  ^  Lately,  carbonate  or  nitrate  of 
baryta,  and  carbonate  with  nitrate  of  lead  have  been  introduced 
into  mineral  analysis  with  great  advantage,  for  the  fluxing  of 
stones  that  may  contain  alkaline  matter. 

Vegetable  Kingdom. 

442.  The  principles  of  which  vegetables  are  composed,  if  we 
pursue  their  analysis  as  far  as  our  means  have  hitherto  allowed, 
are  chiefly  carbon,  hydrogen  and  oxygen.     Nitrogen  is  a  consti- 
tuent principle  of  several,  but  for  the  most  part  in  small  quantity. 
Potash,  soda,  lime,  magnesia,  silex,  alumina,  sulphur,  phospho- 
rus,  iron,   manganese,   and    muriatic   acid   have   likewise   been 
reckoned  in  the  number;  but  some  of  these  occur  only  occasionally, 
and  chiefly  in  very  small  quantities ;  and  are  scarcely  more  enti- 
tled to  be  considered  as  belonging  to  them  than  gold,  or  some 
other  substances  that  have  been  occasionally  procured  from  their 
decomposition. 

443.  The  following  are  the  principal  products  of  vegetation  : — 
(1.)  Sugar.  Crystallizes;  soluble  in  water  and  alcohol;  taste 

sweet ;  soluble  in  nitric  acid,  and  yields  oxalic  acid. 

(2.)  Sarcocoll.  Does  not  crystallize ;  soluble  in  water  and 
alcohol;  taste  bitter  sweet;  soluble  in  nitric  acid,  and  yields 
oxalic  acid. 

(3.)  Jisparagin.  Crystallizes ;  taste  cooling  and  nauseous ; 
soluble  in  hot  water;  insoluble  in  alcohol ;  soluble  in  nitric  acid, 
and  converted  into  bitter  principle  and  artificial  tannin. 

444.  (4.)  Gum.     Does  not  crystallize;  taste  insipid ;  soluble 
in  water,  and  forms  mucilage;  insoluble  in  alcohol;  precipitated 
by  silicated  potash ;  soluble  in  nitric  acid,  and  forms  mucous  and 
oxalic  acids. 

(5.)   Ulmin.     Does  not  crystallize ;   taste  insipid  ;   soluble  in 

How  are  lime  and  baryta  separated  ? 

For  what  purpose  is  boracic  acid  useful  in  analysis  ? 

For  what  analyses  are  carbonates  and  nitrates  of  baryta  and  lead  useful  ? 

What  are  the  simple  substances  chiefly  employed  in  the  composition  of 
vegetables  ? 

What  earthy  and  metallic  ingredients  are  occasionally  met  with  in  ve- 
getable substances  ? 

What  are  the  properties  of  sugar,  sarcocoll,  and  asparagin  ? 

What  common  properties  have  gum  and  ulmin  ? 


VEGETABLE  KINGDOM.  165 

water,  and  does  not  form  mucilage ;  precipitated  by  nitric  and 
hydrochloric  acid  in  the  state  of  resin  ;  insoluble  in  alcohol. 

(G.)  Inulin.  Awhile  powder;  insoluble  in  cold  water ;  solu- 
ble in  boiling  water;  but  precipitates  unaltered  after  the  solution 
cools ;  insoluble  in  alcohol ;  soluble"  in  nitric  acid,  and  yields 
oxalic  acid. 

445.  (7.)  Starch.     A  white  powder ;  taste  insipid  ;  insoluble 
in  cold  water;  soluble  in  hot  water;  opaque  and  glutinous;  pre- 
cipitated by  an  infusion  of  nut-galls ;  precipitate  re-dissolved  by 
a  heat  of  120°  ;  insoluble  in  alcohol ;  soluble  in  dilute  nitric  acid, 
and  precipitated  by  alcohol ;  with  nitric  acid  yields  oxalic  acid 
and  a  waxy  matter. 

(8.)  Indigo.  A  blue  powder,  taste  insipid  ;  insoluble  in  water, 
alcohol,  ether ;  soluble  in  sulphuric  acid;  soluble  in  nitric  acid, 
and  converted  into  bitter  principle  and  artificial  tannin. 

(9.)  Gluten.  Forms  a  ductile  elastic  mass  with  water;  par- 
tially soluble  in  water;  precipitated  by  infusion  of  nut-galls  and 
oxygenized  muriatic  acid ;  soluble  in  acetic  acid  and  muriatic 
acid  ;  insoluble  in  alcohol ;  by  fermentation  becomes  viscid  and 
adhesive,  and  then  assumes  the  properties  of  cheese;  soluble  in 
nitric  acid,  and  yields  oxalic  acid. 

446.  (10.)  Albumen.     Soluble  in  cold  water;   coagulated  by 
heat,  and  becomes  insoluble ;  insoluble  in  alcohol ;  precipitated 
by  infusion  of  nut-galls  ;  soluble  in  nitric  acid  ;  soon  putrefies. 

(11.)  Fibrin.  Tasteless;  insoluble  in  water  and  alcohol;  so- 
luble in  diluted  alkalies,  and  in  nitric  acid  ;  soon  putrefies. 

(12.)  Gelatin.  Insipid;  soluble  in  water  ;  does  not  coagulate 
when  heated  ;  precipitated  by  infusion  of  galls. 

(13.)  Bitter  principle.  Colour  yellow  or  brown  ;  taste  bitter; 
equally  soluble  in  water  and  alcohol ;  soluble  in  nitric  acid  ;  pre- 
cipitated by  nitrate  of  silver. 

447.  (14.)  Extractive.    Soluble  in  water  and  alcohol ;  insoluble 
in  ether;  precipitated  by  oxygenized  muriatic  acid,  muriate  of 
tin,  and  muriate  of  alumina  ;  but  not  by  gelatin  ;  dyes  fawn  colour. 

(15.)  Tannin.  Taste  astringent;  soluble  in  water  and  in  alco- 
hol of  sp.  grav.  0.810 ;  precipitated  by  gelatin,  muriate  of  alumina, 
and  muriate  of  tin. 

(16.)  Fixed  oils.  No  smell ;  insoluble  in  water  and  alcohol ; 
form  soaps  with  alkalies  ;  coagulated  by  earthy  and  metallic  salts. 

(17.)  Wax.  Insoluble  in  water;  soluble  in  alcohol,  ether,  and 
oilsj  forms  soap  with  alkalies ;  fusible. 

448.  (18.)    Volatile  oil.     Strong  smell;  insoluble  in  water; 
soluble  in  alcohol ;  liquid  ;  volatile  ;  oily ;  by  nitric  acid  inflamed, 
and  converted  into  resinous  substances. 

What  difference  of  properties  exists  between  inulin  and  starch? 

What  are  the  peculiar  properties  of  indigo?  What  are  the  distinctive 
characters  of  gluten  ?  How  are  albumen,  fibrin,  and  gelatin  distinguished  ? 

Give  the  respective  distinctive  characters  of  bitter  principle,  extractive, 
and  tannin.  What  are  the  marked  differences  between  fixed  oils,  wax, 
and  volatile  oils  ? 


1G6  CHEMISTRY. 

(19.)  Camphor.  Strong  odour;  crystallizes;  very  little  soluble 
in  water ;  soluble  in  alcohol,  oils,  acids;  insoluble  in  alkalies; 
burns  with  a  clear  flame,  and  volatilizes  before  melting1. 

(20.)  Birdlime.  Viscid;  taste  insipid;  insoluble  in  water; 
partially  soluble  in  alcohol  ;~very  soluble  in  ether;  solution  green. 

449.  (21.)    Resins.     Solid;    melt  when  heated;    insoluble  in 
water;  soluble  in  alcohol,  ether,  and  alkalies;  soluble  in  acetic 
acid  ;  by  nitric  acid  converted  into  artificial  tannin. 

(22.)  Guaiacum.  Possesses  the  characters  of  resins ;  but  dis- 
solves in  nitric  acid,  and  yields  oxalic  acid  and  no  tannin. 

(23.)  Balsams.  Possess  the  characters  of  the  resins,  but  have 
a  strong1  smell ;  when  heated,  benzoic  acid  sublimes  ;  it  sublimes 
also  wfien  they  are  dissolved  in  sulphuric  acid  ;  by  nitric  acid 
converted  into  artificial  tannin. 

450.  (24.)    Caoutchouc.     Very  elastic ;  insoluble  in  water  and 
alcohol  ;  when  steeped    in  ether,  reduced  to  a  pulp,  which  ad- 
heres to  every  thing ;  fusible,  and  remains  liquid  ;  very  combus- 
tible. 

(25.)  Gum  resins.  Form  milky  solutions  with  water,  transpa- 
rent with  alcohol ;  soluble  in  alkalies  ;  with  nitric  acid  converted 
into  tannin ;  strong  smell  ;  brittle,  opaque,  infusible. 

(26.)  Cotton.  Composed  of  fibres;  tasteless;  very  combusti- 
ble;  insoluble  in  water,  alcohol,  and  ether ;  soluble  in  alkalies; 
yields  oxalic  acid  and  nitric  acid. 

451.  (27.)    Suber.     Burns  bright  and  swells;    converted  by 
nitric  acid  into  suberic  acid  and  wax ;  partially  soluble  in  water 
and  alcohol. 

(28.)  Wood.  Composed  of  fibres,  tasteless;  insoluble  in  water 
and  alcohol;  soluble  in  weak  alkaline  lixivium;  precipitated  by 
acids;  leaves  much  charcoal  when  distilled  in  a  red  heat;  soluble 
in  nitric  acid,  and  yields  oxalic  acid. 

452.  To  the  preceding  we  may  add,  emetin,  fungin,  hematin, 
nicotin,  pollenin,  solanine,  caffein,  narcotine;  the  new  vegetable 
alkalies,  aconita,  atropia,  brucia,  cinchonia,  cicuta,  datura,  delphia, 
hyosciama,  morphia,  picrotoxia,  quinia,  corydalia,  guarania,  stron- 
tia,  veratria ;  and  various  vegetable  acids. 

MM.  Dumas  and  Pelletier  have  published  a  memoir  on  the  ele- 
mentary composition  and  certain  characteristic  properties  of  the 
organic  salifiable  bases  (vegeto-alkalies.)  The  following  is  a 
tabular  view  of  the  relations  of  carbon  and  azote  in  these  alkaline 
bodies. 


What  are  the  distinctive  characters  of  camphor?  bird-lime  ? 
What  similarities  and  what  differences  are  remarked  between  resins  and 
balsams  ? 

How  are  gum  resins  characterized  ? 
In  what  substances  is  cotton  soluble? 
What  product  does  it  yield  when  tested  with  nitric  acid? 
In  what  substances  is  suber  soluble  ?  in  what  is  wood  soluble  ? 


ANALYSIS  OF  VEGETABLES.  167 

Carbonic  acid.  Azote. 

Quinia,  100  .  5.1 

Cinchonia,  100  .  5.0 

Strychnia,  100  .  4.9 

Narcotine,  100  .  4.5 

Brucina,  100  .  5.0 

Morphia,  100  .  3.2 

Veratria,  100  .  3.2 

Emetin,  100  .  3.1 

Caffein,  100  .  20.0 

Analysis  of  Vegetables. 

/•',  453.  The  analysis  of  vegetables  requires  various  manipulations 
and  peculiar  attention,  as  their  principles  are  extremely  liable  to 
be  altered  by  the  processes  to  which  they  are  subjected.  It  was 
long  before  this  analysis  was  brought  to  any  degree  of  perfection. 

454.  Some  of  the  immediate  materials  of  vegetables  are  sepa- 
rated to  our  hands  by  nature  in  a  state  of  greater  or  less  purity ; 
as  the  gums,  resins,  and  balsams,  that  exude  from  plants.     The 
expressed  juices  contain  various  matters  that  may  be  separated 
by  the  appropriate  reagents.    Maceration,  infusion,  and  decoction 
in  water,  take  up  certain  parts  soluble  in  this  menstruum ;  and 
alcohol  will  extract  others  that  water  will  not  dissolve. 

455.  As  the  ultimate  constituents  of  all  vegetable  substances 
are  carbon,  hydrogen,  and  oxygen,  with  occasionally  azote,  the 
problem  of  their  final  analysis  resolves  into  a  method  of  ascer- 
taining the  proportion  of  these  elementary  bodies.      MM.  Gay 
Lussac  and  Thenard  contrived  a  very  elegant  apparatus  for  vege- 
table and  animal  analysis,  in  which  the  matter  in  a  dried  state  was 
mixed  with  chlorate  of  potash,  and  formed  into  minute  pellets. 
These  pellets  being  projected  through  the  intervention  of  a  stop- 
cock of  peculiar  structure  into  an  ignited  glass  tube,  were  instantly 
resolved  into  carbonic  acid  and  water.     The  former  product  was 
received  over  mercury,  and  estimated  by  its  condensation  with 
potash ;  the  latter  was  intercepted  by  ignited  muriate  of  lime,  and 
was  measured  by  the  increase  of  weight  which  it  communicates 
to  this  substance.     By  previous  trials,  the  quantity  of  oxygen 
which  a  given  weight  of  the  chlorate  of  potash  yielded  by  igni- 
tion was  known ;  and  hence  the  carbon,  hydrogen,  and  oxygen, 
derived  from  the  organic  substance,  as  well  as  the  residual  azote 
of  the  gaseous  products  were  determined.    . 

456.  M.  Berzelius  modified  the  above  apparatus,  and  employed 
the  organic  products  in  combination  with  a  base,  generally  oxide 
of  lead.     He  mixed  a  certain  weight  of  this  neutral  compound 
with  a  known  quantity  of  pure  chlorate  of  potash,  and  triturated 
the  whole  with  a  large  quantity  of  muriate  of  soda,  for  the  pur- 

What  proportions  have  the  vegeto-alkalies  been  found  to  contain  of 
carbonic  acid  and  azote  ?  What  circumstance  renders  vegetable  analysis 
more  difficult  than  that  of  minerals  ? 

What  is  the  great  question  to  be  solved  in  the  analysis  of  vegetables  ? 

How  did  Gay  Lussac  and  Thenard  execute  their  analyses  ? 


1 68  CHEMISTRY. 

pose  of  moderating  the  subsequent  combustion.  This  mingled 
dry  powder  is  put  into  a  glass  tube  about  half  an  inch  in  diameter, 
and  eight  or  ten  inches  long,  which  is  partially  enclosed  in  a  fold 
of  tin-plate,  hooped  with  iron  wire.  One  end  of  the  tube  is  her- 
metically sealed  beforehand,  the  other  is  now  drawn  to  a  pretty 
fine  point  by  the  blowpipe.  This  termination  is  inserted  into  a 
glass  globe  about  an  inch  in  diameter,  which  joins  it  to  a  long 
tube  containing  dry  muriate  of  lime  in  its  middle,  and  dipping  at 
its  other  extremity  into  the  mercury  of  a  pneumatic  trough.  The 
first  tube,  with  its  protecting  tin  case,  being  exposed  gradually  to  ig- 
nition, the  enclosed  materials  are  resolved  into  carbonic  acid,  water, 
and  azote,  which  come  over,  and  are  estimated  as  above  described. 

457.  M.  Gay  Lussac  has  more  recently  employed  peroxide  of 
copper  to  mix  with  the  organic  substance  to  be  analyzed  ;  because, 
while  it  yields  its  oxygen  to  hydrogen  and  carbon,  it  is  not  acted 
on  by  azote  ;  and  thus  the  errors  resulting  from  the  formation  of 
nitric  acid  with  the  chlorate  of  potash  are  avoided.    Berzelius  has 
afforded  satisfactory  evidence  by  his  analyses,  that  the  simple 
apparatus  which  he  employed  is  adequate  to  every  purpose  of 
chemical  research.* 

Animal  Kingdom. 

458.  Animal  bodies  may  be  considered  as  peculiar  apparatus 
for  carrying  on  a  determinate  series  of  chemical  operations.    Ve- 
getables seem  capable  of  operating  with  fluids  only,  and  at  the 
temperature  of  the  atmosphere.     But  most  animals  have  a  provi- 
sion for  mechanically  dividing  solids  by  mastication,  which  an- 
swers the  same  purpose  as  grinding,  pounding,  or  levigation  does 
in  our  experiments  ;  that  is  to  say,  it  enlarges  the  quantity  of  sur- 
face to  be  acted  upon  by  solvents. 

459.  The  process  carried  on  in  the  stomach  appears  to  be  of  the 
same  kind  as  that  which  we  distinguish  by  the  name  of  digestion ; 

What  method  did  Berzelius  employ  to  obtain  and  estimate  the  compo- 
nents of  vegetable  matter  ? 
In  what  light  may  animal  bodies  be  considered  ? 

*  Perhaps  one  of  the  most  curious  substances  of  a  vegetable  character 
that  has  hitherto  been  analyzed,  is  the  inflammable  snow  which  fellon  the 
llth  of  April,  1832,  not  far  from  VVolokalamsk,  and  covered  a  consider- 
able extent  of  ground  to  the  depth  of  one  or  two  inches.  This  substance 
was  of  a  yellowish  tint,  transparent,  soft,  and  elastic;  insipid,  but  having 
the  odour  of  rancid  oil.  Its  sp.  grav.  was  1.1.  It  melted  when  heated  in 
a  close  vessel,  and  yielded,  by  distillation,  the  usual  products  of  vegetable 
substances,  leaving  a  b'rilliant  charcoal.  It  burned  with  a  blue  flame, 
without  smoke ;  was  insoluble  in  cold  water,  but  melted  and  floated  on 
the  surface  of  boiling  water;  was  dissolved  by  boiling  alcohol,  and  in  car- 
bonate of  soda,  and  acids,  and  threw  down  from  this  latter  solution  a  yel- 
low viscid  substance,  soluble  in  cold  alcohol,  and  ^which  contained  a  pe- 
culiar acid.  The  analysis  by  means  of  the  oxide  of  copper,  gave  from 
this  substance — 


Carbon, 0.615. ) 

Hydrogen, 0.070.  V  1.000. 

Oxygen, 0.315.) 


Oxygt 

M.  Herman,  who  analyzed  this  substance,  gave  it  the  name  of  oil  of 
heaven.    This  material  is  supposed  to  be  the  pollen  of  pine  or  fir  trees.  ED 


ANIMAL  KINGDOM.  169 

and  the  bowels,  whatever  other  uses  they  may  serve,  evidently 
form  an  apparatus  for  filtering  or  conveying  off  the  fluids  ;  while 
the  more  solid  parts  of  the  aliments,  which  are  probably  of  such 
a  nature  as  not  to  be  rendered  fluid,  but  by  an  alteration  which 
would  perhaps  destroy  the  texture  of  the  machine  itself,  are  re- 
jected as  useless. 

460.  When  this  filtered  fluid  passes  into  the  circulatory  vessels, 
through  which  it  is  driven  with  considerable  velocity  by  the  me- 
chanical action  of  the  heart,  it  is  subjected  not  only  to  all  those 
changes  which  the  chemical  action  of  its  parts  is  capable  of  pro- 
ducing, but  is  likewise  exposed  to  the  air  of  the  atmosphere  in 
the  lungs,  into  which  that  elastic  fluid  is  admitted  by  the  act  of 
respiration.     Here  it  undergoes  a  change  of  the  same  nature  as 
happens  to  other  combustible  bodies,  when  they  combine  with  its 
vital  part,  or  oxygen.     This  vital  part  becomes  condensed,  and 
combines  with  the  blood,  at  the  same  time  that  it  gives  out  a  large 
quantity  of  heat,  in  consequence  of  its  own  capacity  for  heat 
being  diminished.    A  small  portion  of  azote  likewise  is  absorbed, 
and  carbonic  acid  is  given  out. 

461.  Some  curious  experiments  of  Spallanzani  show,  that  the 
lungs  are  not  the  sole  organs  by  which  these  changes  are  effected. 
Worms,  insects,  shells  of  land  and  sea  animals,  egg  shells,  fishes, 
dead  animals,  and  parts  of  animals,  even  after  they  have  become 
putrid,  are  capable  of  absorbing  oxygen  from  the  air,  and  giving 
out  carbonic  acid.     They  deprive  atmospheric  air  of  its  oxygen 
as  completely  as  phosphorus.    Shells,  however,  lose  this  property 
when  their  organization  is  destroyed  by  age.  Amphibia,  deprived 
of  their  lungs,  lived  much  longer  in  the  open  air,  than  others  in 
air  destitute  of  oxygen.     It  is  remarkable,  that  a  larva,  weighing 
a  few  grains,  would  consume  almost  as  much  oxygen  in  a  given 
time,  as  one  of  the  amphibia  a  thousand  times  its  bulk. 

462.  The  following  are  the  peculiar  chemical  products  of  ani- 
mal organization : — Gelatin,  albumen,  fibrin,  fat,  caseous  matter, 
colouring  matter  of  blood,  mucus,  urea,  picromel,   osmazome, 
sugar  of  milk,  and  sugar  of  diabetes.     The  compound  animal 
products  are  the  various  solids  and  fluids,  whether  healthy  or 
moroid,  that  are  found  in  the  animal  body ;  such  as  muscle,  skin, 
bone,  blood,  urine,  bile,  morbid  concretions,  brain,  &c. 

463.  When  animal  substances  are  left  exposed  to  the  air,  or 
immersed  in  water  or  other  fluids,  they  surfer   a   spontaneous 
change,  which  is  more  or  less  rapid  according  to  circumstances. 
The  spontaneous  change  of  organized  bodies  is  distinguished  by 
the  name  of  fermentation.     In  vegetable  bodies  there  are  distinct 
stages  or  periods  of  this  process,  which  have  been  divided  into 

What  chemical  office  does  the  stomach  of  animals  perform? 

Into  what  vessels  do  the  liquids  JUtered  by  the  alimentary  canals  next  pass  ? 

What  curious  facts  has  Spallanzani  observed  in  regard  to  the  respiration 
of  animals?  What  are  the  products  of  the  processes  performed  by  the  or- 
gans of  animals  ? 

How  is  the  decomposition  of  animal  substances  naturally  effected? 


170  CHEMISTRY. 

the  vinous,  acetous,  and  putrefactive  fermentations.  Animal  sub- 
stances are  susceptible  only  of  the  two  latter,  during  which,  as 
in  all  other  spontaneous  changes,  the  combinations  of  chemical 
principles  become  in  general  more  and  more  simple.  There  is  no 
doubt  but  much  instruction  might  be  obtained  from  accurate  ob- 
servations of  the  putrefactive  processes  in  all  their  several  varie- 
ties and  situations ;  but  the  loathsomeness  and  danger  attending 
on  such  inquiries  have  hitherto  greatly  retarded  our  progress  in 
this  department  of  chemical  science. 

Soils. 

464.  The  soil  or  earth  in  which  vegetables  grow  varies  con- 
siderably in  its  composition,  or  in  the  proportions  of  the  different 
earths  of  which  it  consists ;  and  some  plants  are  found  to  thrive 
best  in  one  kind  of  soil,  others  in  another. 

465.  In  cases  where  a  barren  soil  is  examined  with  a  view  to 
its  improvement,  it  ought  in  all  cases,  if  possible,  to  be  compared 
with  an  extremely  fertile  soil  in  the  same  neighbourhood,  and  in 
a  similar  situation  :  the  difference  given  by  their  analyses  would 
indicate  the  methods  of  cultivation,  and  thus  the  plan  of  improve- 
ment would  be  founded  upon  accurate  scientific  principles. 

466.  If  the  fertile  soil  contained  a  large  quantity  of  sand,  in 
proportion  to  the  barren  soil,  the  process  of  melioration  would 
depend  simply  upon  a  supply  of  this  substance ;  and  the  method 
would  be  equally  simple  with  regard  to  soils  deficient  in  clay  or 
calcareous  matter. 

467.  In  the  application  of  clay,  sand,  loam,  marl,  or  chalk,  to 
lands,  there  are  no  particular  chemical  principles  to  be  observed  ; 
but  when  quicklime  is  used,  great  care  must  be  taken,  that  it  is 
not  obtained  from  the  magnesian  limestone;  for  in  this  case,  as  has 
been  shown  by  Mr.  Tennant,  it  is  exceedingly  injurious  to  land. 
The  magnesian  limestone  may  be  distinguished  from  the  common 
limestone  by  its  greater  hardness,  and  by  the  length  of  time  that 
it  requires  for  its  solution  in  acids ;  and  it  may  be  analyzed  by 
the  process  for  carbonate  of  lime  and  magnesia. 

468.  When  the  analytical  comparison  indicates  an  excess  of 
vegetable  matter  as  the  cause  of  sterility,  it  may  be  destroyed  by 
much  pulverization  and   exposure  to  air,  by  paring  and  burning, 
or  the  agency  of  lately-made  quicklime.     And  the  defect  of  ani- 
mal and  vegetable  matter  must  be  supplied  by  animal  or  vegetable 
manure. 

469.  The  general  indications  of  fertility  and  barrenness,  as  found 
by  chemical  experiments,  must  necessarily  differ  in  different  cli- 

Tlirough  how  many  stages  of  fermentation  do  vegetable  and  how  many 
do  animal  substances  pass  during  decomposition  ? 

In  what  manner  ought  soils  to  be  compared  with  a  view  to  improve- 
ments in  their  composition  ? 

What  example  of  alteration  in  soil  may  illustrate  this  point? 

VVhat  precaution  is  to  be  used  in  attempting  to  improve  soils  by  means 
of  lime  ? 

flow  is  an  excess  of  vegetable  mould  in  any  given  soil  to  be  obviated  ? 

How  is  its  deficiency  to  be  supplied  ? 


SOILS.  171 

mates,  and  under  different  circumstances.  The  power  of  soils  to 
absorb  moisture,  a  principle  essential  to  their  productiveness,  ought 
to  be  much  greater  in  warm  and  dry  countries  than  in  cold  and 
moist  ones ;  and  the  quantity  of  fine  aluminous  earth  they  contain 
should  be  larger.  Soils  likewise  that  are  situate  on  declivities 
ought  to  be  more  absorbent  than  those  in  the  same  climate  on 
plains  or  in  valleys. 

470.  The  productiveness  of  soils  must  likewise  be  influenced 
by  the  nature  of  the  sub-soil,  or  the  earthy  or  stony  strata  on 
which  they  rest ;  and  this  circumstance  ought  to  be  particularly 
attended  to,  in  considering  their  chemical  nature,  and  the  system 
of  improvement.     Thus  a  sandy  soil  may  owe  its  fertility  to  the 
power  of  the  sub-soil  to  retain  water ;  and  an  absorbent  clayey 
soil  may  occasionally  be  prevented  from  being  barren,  in  a  moist 
climate,  by  the  influence  of  a  sub-stratum  of  sand  or  gravel. 

471.  Those  soils  that  are  most  productive  of  corn,  contain  always 
certain  proportions  of  aluminous  or  calcareous  earth  in  a  finely 
divided  state,  and  a  certain  quantity  of  vegetable  or  animal  matter. 

Mr.  Tillet,  in  some  experiments  made  on  the  composition  of 
soils  at  Paris,  found,  that  a  soil  composed  of  three-eighths  of  clay, 
two-eighths  of  river  sand,  and  three-eighths  of  the  parings  of  lime- 
stone, was  very  proper  for  wheat. 

472.  In  general,  bulbous  roots  require  a  soil  much  more  sandy, 
and  less  absorbent,  than  the  grasses.     A  very  good  potato  soil, 
from  Varsel,  in  Cornwall,  afforded  seven-eighths  of  siliceous  sand  ; 
and  its  absorbent  power  was  so  small,  that  100  parts  lost  only  2 
by  drying  at  400°  Fahrenheit. 

Plants  and  trees,  the  roots  of  which  are  fibrous  and  hard,  and 
capable  of  penetrating  deep  into  the  earth,  will  vegetate  to  ad- 
vantage in  almost  all  common  soils  that  are  moderately  dry,  and 
do  not  contain  a  very  great  excess  of  vegetable  matter. 

473.  From  the  great  difference  of  the  causes  that  influence  the 
productiveness  of  lands,  it  is  obvious,  that  in  the  present  state  of 
science  no  certain  system  can  be  devised  for  their  improvement, 
independent  of  experiment;  but  there  are  few  cases,  in  which  the 
labour  of  analytical  trials  will  not  be  amply  repaid  by  the  cer- 
tainty with  which  they  denote  the  best  methods  of  melioration ; 
and  this  will  particularly  happen,  when  the  defect  of  composition 
is  found  in  the  proportions  of  the  primitive  earths. 

474.  In  supplying  animal  or  vegetable  manure,  a  temporary 
food  only  is  provided  for  plants,  which  is  in  all  cases  exhausted 
by  "means  of  a  certain  number  of  crops;  but  when  a  soil  is  ren- 

What  principle  is  essential  to  the  productiveness  of  soils  ? 

What  influence  may  the  rock  over  which  any  soil  lies  exercise  on  its 
productiveness  ?  What  example  may  be  adduced  of  this  fact  ? 

What  ingredient  seems  peculiarly  favourable  to  the  production  of 
grain  ? 

What  composition  did  Tillet  find  adapted  to  this  purpose  ? 

What  soil  is  best  adapted  to  bulbous  roots  ? 

What  advantage  do  trees  possess  in  regard  to  variety  of  soils  ? 

Under  what  circumstances  may  we  expect  the  greatest  advantages  from 
studying  the  chemical  composition  of  soils  ? 


172  CHEMISTRY. 

dered  of  the  best  possible  constitution  and  texture  with  regard  to 
its  earthy  parts,  its  fertility  may  be  considered  as  permanently 
established.  It  becomes  capable  of  attracting  a  very  large  portion 
of  vegetable  nourishment  from  the  atmosphere,  and  of  producing 
its  crops  with  comparatively  little  labour  and  expense. 

Analysis  of  Soils. 

475.  The  substances  found  in  soils  are  certain  mixtures  or  com- 
binations of  some  of  the  primitive  earths,  animal  and  vegetable 
matter  in  a  decomposed  state,  certain  saline  compounds,  and  the 
oxide  of  iron.     These  bodies  always  retain  water,  and  exist  in 
very  different  proportions  in  different  lands,  and  the  end  of  ana- 
lytical experiments  is  the  detection  of  their  quantities  and  mode 
of  union. 

The  earths  commonly  found  in  soils  are  principally  silex,  or  the 
earth  of  flints;  alumina  or  the  pure  matter  of  clay;  lime,  or  cal- 
careous earth ;  and  magnesia. 

476.  Animal   decomposing  matter   exists   in  different  states, 
contains  much  carbonaceous  substance,  volatile  alkali,  inflamma- 
ble aeriform  products,  and  carbonic  acid.     It  is  found  chiefly  in 
lands  lately  manured.     Vegetable  decomposing  matter  usually 
contains  still  more  carbonaceous  substance,  and  differs  from  the 
preceding,  principally,  in  not  producing  volatile  alkali.     It  forms 
a  great  proportion  of  all  peats,  abounds  in  rich  mould,  and  is 
found  in  larger  or  smaller  quantities  in  all  lands. 

477.  The  saline  compounds  are  few,  and  in  small  quantity : 
they  are  chiefly  muriate  of  soda,  or  common  salt,  sulphate  of 
magnesia,  muriate  and  sulphate  of  potash,  nitrate  of  lime,  and  the 
mild  alkalies.     Oxide  of  iron,  which  is  the  same  with  the  rust 
produced  by  exposing  iron  to  air  and  water,  is  found  in  all  soils, 
but  most  abundantly  in  red  and  yellow  clays,  and  red  and  yellow 
siliceous  sands. 

478.  The  instruments  requisite  for  the  analysis  of  soils  are  few. 
A  pair  of  scales  capable  of  holding  a  quarter  of  a  pound  of  com- 
mon soil,  and  turning  with  a  single  grain  when  loaded ;  a  set  of 
weights,  from  a  quarter  of  a  pound  troy  to  a  grain ;  a  wire  sieve, 
coarse  enough  to  let  a  pepper-corn  pass  through  ;  an  Argand  lamp 
and  stand ;  a  few  glass  bottles,  Hessian  crucibles,  and  china  or 
queen's  ware  evaporating  basin  ;  a  wedgwood  pestle  and  mortar; 
some  filters  made  of  half  a  sheet  of  blotting  paper,  folded  so  as 
to  contain  a  pint  of  liquid,  and  greased  at  the  edges  ;  a  bone  knife ; 
and  an  apparatus  for  collecting  and  measuring  aeriform  fluids. 

Why  is  it  more  important  to  ascertain  a  defect  in  soils  with  regard  to 
the  primitive  earths  than  to  the  vegetable  or  animal  ingredients? 
What  variety  of  substances  enter  into  the  composition  of  soils? 
What  four  earths  exist  in  the  greatest  abundance  in  soils  ? 
On  what  lands  is  animal  matter  usually  found  ? 
Of  what  substances  is  it  found  to  consist  ? 

How  do  the  vegetable  differ  from  the  animal  components  of  soils? 
What  are  the  saline  ingredients  of  soils? 
What  metallic  oxide  exists  in  them  ? 
With  what  chemical  apparatus  may  soils  be  analyzed  ? 


ANALYSIS  OF  SOILS.  173 

479.  The  reagents  necessary  are  muriatic  acid,  sulphuric  acid, 
pure  volatile  alkali  dissolved  in  water,  solution  of  prussiate  of 
potash,  soap  lye,  and  solutions  of  carbonate  of  ammonia,  muriate 
of  ammonia,  neutral  carbonate  of  potash,  and  nitrate  of  ammonia. 

(1.)  When  the  general  nature  of  the  soil  of  a  field  is  to  be 
ascertained,  specimens  of  it  should  be  taken  from  different  places, 
two  or  three  inches  below  the  surface,  and  examined  as  to  the 
similarity  of  their  properties.  It  sometimes  happens,  that  on 
plains  the  whole  of  the  upper  stratum  of  the  lands  is  of  the  same 
kind,  and  in  this  case  one  analysis  will  be  sufficient.  But  in  val- 
leys, and  near  the  beds  of  rivers,  there  are  very  great  differences, 
and  it  now  and  then  occurs,  that  one  part  of  a  field  is  calcareous, 
and  another  part  siliceous  ;  in  this  and  analogous  cases,  the  por- 
tions different  from  each  other  should  be  analyzed  separately. 
Soils,  when  collected,  if  they  cannot  be  examined  immediately, 
should  be  preserved  in  phials,  quite  filled  with  them,  and  closed 
with  ground  glass  stopples. 

480.  The  most  convenient  quantity  for  a  perfect  analysis  is  from 
two  hundred  grains  to  four  hundred.     It  should  be  collected  in 
dry  weather,  and  exposed  to  the  air  till  it  feels  dry.     Its  specific 
gravity  may  be  ascertained,  by  introducing  into  a  phial,  which 
will  contain  a  known  quantity  of  water,  equal  bulks  of  water  and 
of  the  soil;  which  may  easily  be  done  by  pouring  in  water  till 
the  phial  is  half  full,  and  then  adding  the  soil  till  the  fluid  rises 
to  the  mouth.     The  difference  between  the  weight  of  the  water 
and  that  of  the  soil  will  give  the  result.     Thus,  if  the  bottle  will 
contain  four  hundred  grains  of  water,  and  gains  two  hundred  grains 
when  half  filled  with  water  and  half  with  soil,  the  specific  gravity 
of  the  soil  will  be  2 ;  that  is,  it  will  be  twice  as  heavy  as  water : 
and  if  it  gained  one  hundred  and  sixty-five  grains,  its  specific 
gravity  would  be  1825,  water  being  1000.     It  is  of  importance 
that  the  specific  gravity  of  a  soil  should  be  known,  as  it  affords 
an  indication  of  the  quantity  of  animal  and  vegetable  matter  it 
contains ;  these  substances  being  always  most  abundant  in  the 
lighter  soils.     The  other  physical  properties  of  soils  should  like- 
wise be  examined  before  the  analysis  is  made,  as  they  denote,  to 
a  certain  extent,  their  composition,  and  serve  as  guides  in  direct- 
ing the  experiments.    Thus,  siliceous  soils  are  generally  rough  to 
the  touch,  and  scratch  glass  when  rubbed  upon  it ;  aluminous  soils 
adhere  strongly  to  the  tongue,  and  emit  a  strong  earthy  smell 
when  breathed  upon  ;  and  calcareous  soils  are  soft,  and  much  less 
adhesive  than  aluminous  soils. 

481.  (2.)  Soils,  when  as  dry  as  they  can  be  made  by  exposure  to 
the  air,  still  retain  a  considerable  quantity  of  water,  which  adheres 

What  chemical  tests  are  required  ? 

In  what  manner  ought  specimens  of  soil  for  examination  to  be  collected 
and  preserved  ? 

In  what  manner  is  the  specific  gravity  of  soils  ascertained  ? 
Why  is  this  step  important  ? 
What  other  physical  properties  are  to  be  tried  ? 
P2 


174  CHEMISTRY. 

with  great  obstinacy  to  them,  and  cannot  be  driven  off  without 
considerable  heat :  and  the  first  process  of  analysis  is  to  free  them 
from  as  much  of  this  water  as  possible,  without  affecting  their 
composition  in  other  respects.  This  may  be  done  by  heating  the 
soil  for  ten  or  twelve  minutes  in  a  china  basin  over  an  Argand 
lamp,  at  a  temperature  equal  to  300°  F. ;  and  if  a  thermometer  be 
not  used,  the  proper  degree  of  heat  may  easily  be  ascertained  by 
keeping  a  piece  of  wood  in  the  basin  in  contact  with  its  bottom  ; 
for  as  long  as  the  colour  of  the  wood  remains  unaltered,  the  heat 
is  not  too  high  ;  but  as  soon  as  it  begins  to  be  charred,  the  process 
must  be  stopped.  In  several  experiments,  in  which  Sir  H.  Davy 
collected  the  water  that  came  over  at  this  degree  of  heat,  he  found 
it  pure,  without  any  sensible  quantity  of  other  volatile  matter  being 
produced.  The  loss  of  weight  in  this  process  must  be  carefully 
noted ;  and  if  it  amount  to  50  grains  in  400  of  the  soil,  this  may 
be  considered  as  in  the  greatest  degree  absorbent  and  retentive  of 
water,  and  will  generally  be  found  to  contain  a  large  proportion 
of  aluminous  earth.  If  the  loss  be  not  more  than  10  or  20  grains, 
the  land  may  be  considered  as  slightly  absorbent  and  retentive, 
and  the  siliceous  earth  as  most  abundant. 

482.  (3.)  None  of  the  loose  stones,  gravel,  or  large  vegetable 
fibres,  should  be  separated  from  the  soil,  till  the  water  is  thus  ex- 
pelled ;  for  these  bodies  are  often  highly  absorbent  and  retentive, 
and  consequently  influence  the  fertility  of  the  land.    But  after  the 
soil  has  been  heated  as  above,  these  should  be  separated  by  the 
sieve,  after  the  soil  has  been  gently  bruised  in  a  mortar.     The 
weights  of  the  vegetable  fibres  or  wood,  and  of  the  gravel  and 
stones,  should  be  separately  noted  down,  and  the  nature  of  the  latter 
ascertained  :  if  they  be  calcareous,  they  will  effervesce  with  acids; 
if  siliceous  they  will  scratch  glass;  if  aluminous,  they  will  be 
soft,  easily  scratched  with  a  knife,  and  incapable  of  effervescing 
with  acids. 

483.  (4.)  Most  soils,  besides  stones  and  gravel,  contain  larger 
or  smaller  proportions  of  sand  of  different  degrees  of  fineness ; 
and  the  next  operation  necessary  is  to  separate  this  sand  from  the 
parts  more  minutely  divided,  such  as  clay,  loam,  marl,  and  vege- 
table and  animal  matter.   This  may  be  done  sufficiently  by  mixing 
the  soil  well  with  water ;  as  the  coarse  sand  will  generally  fall  to 
the  bottom  in  the  space  of  a  minute,  and  the  finer  in  two  or  three : 
so  that  by  pouring  the  water  off  after  one,  two,  or  three  minutes, 
the  sand  will  be,  for  the  most  part,  separated  from  the  other  sub- 
stances ;  which,  with  the  water  containing  them,  must  be  poured 
into  a  filter.     After  the  water  has  passed  through,  what  remains 
on  the  filter  must  be  dried  and  weighed,  as  must  also  the  sand  ; 
and  their  respective  quantities  must  be  noted  down.     The  water 

What  is  ihe  first  step  in  examining  the  composition  of  a  soil  ? 
At  what  temperature  may  it  be  dried  ? 
Why  should  not  the  pebbles  be  separated  before  drying  ? 
How  is  sand  to  be  separated  from  minute  ingredients  ? 


ANALYSIS  OF  SOILS.  175 

must  be  preserved,  as  it  will  contain  the  saline  matter,  and  the 
soluble  animal  or  vegetable  matter,  if  any  existed  in  the  soil. 

481.  (5.)  A  minute  analysis  of  the  sand  thus  separated  is  sel- 
dom or  never  necessary,  and  its  nature  may  be  detected  in  the 
same  way  as  that  of  the  stones  and  gravel.  It  is  always  siliceous 
sand,  or  calcareous  sand,  or  both  together.  If  it  consist  wholly 
of  carbonate  of  lime,  it  will  dissolve  rapidly  in  muriatic  acid,  with 
effervescence ;  but  if  it  consist  partly  of  this  and  partly  of  sili- 
ceous matter,  a  residuum  will  be  left  after  the  acid  has  ceased  to 
act  on  it,  the  acid  being  added  till  the  mixture  has  a  sour  taste, 
and  has  ceased  to  effervesce.  This  residuum  is  the  siliceous  part; 
which  being  washed,  dried,  and  heated  strongly  in  a  crucible,  the 
difference  of  its  weight  from  that  of  the  whole,  will  indicate  the 
quantity  of  the  calcareous  sand. 

485.  (6.)  The  finely  divided  matter  of  the  soil  is  usually  very 
compound  in  its  nature :  it  sometimes  contains  all  the  four  primi- 
tive earths  of  soils,  as  well  as  animal  and  vegetable  matter;  and 
to  ascertain  the  proportions  of  these  with  tolerable  accuracy,  is 
the  most  difficult  part  of  the  subject.    The  first  process  to  be  per- 
formed in  this  part  of  the  analysis,  is  the  exposure  of  the  fine 
matter  of  the  soil  to  the  action  of  muriatic  acid.     This  acid, 
diluted  with  double  its  bulk  of  water,  should  be  poured  upon  the 
earthy  matter  in  an  evaporating  basin,  in  a  quantity  equal  to  twice 
the  weight  of  the  earthy  matter.     The  mixture  should  be  often 
stirred,  and  suffered  to  remain  for  an  hour,  or  an  hour  and  a  half, 
before  it  is  examined. 

486.  If  any  carbonate  of  lime,  or  of  magnesia,  exist  in  the  soil, 
they  will  have  been  dissolved  in  this  time  by  the  acid,  which 
sometimes  takes  up  likewise  a  little  oxide  of  iron,  but  very  sel- 
dom any  alumina.     The  fluid  should  be  passed  through  a  filter ; 
the  solid  matter  collected,  washed  with  distilled  or  rain  water, 
dried  at  a  moderate  heat,  and  weighed.    Its  loss  will  denote  the 
quantity  of  solid  matter  taken  up.     The  washings  must  be  added 
to  the  solution ;  which,  if  not  sour  to  the  taste,  must  be  made  so 
by  the  addition  of  fresh  acid  ;  and  a  little  solution  of  prussiate  of 
potash  must  be  mixed  with  the  liquor.    If  a  blue  precipitate  occur, 
it  denotes  the  presence  of  oxide  of  iron,  and  the  solution  of  the 
prussiate  must  be  dropped  in,  till  no  further  effect  is  produced. 
To  ascertain  its  quantity  it  must  be  collected  on  a  filter  in  the 
same  manner  as  the  other  solid  precipitates,  and  heated  red :  the 
result  will  be  oxide  of  iron. 

^87.  Into  the  fluid  freed  from  oxide  of  iron,  a  solution  of  car- 
bonate of  potash  must  be  poured,  till  all  effervescence  ceases  in 
it,  and  till  its  taste  and  smell  indicate  a  considerable  excess  of 
alkaline  salt.  The  precipitate  that  falls  down  is  carbonate  of 

How  may  the  nature  of  the  sand  be  ascertained  ? 

How  are  we  to  proceed  in  determining  the  finer  portions  of  the  soil  ? 

What  acid  is  first  employed  ? 

What  ingredients  will  this  acid  dissolve  ?  . 

How  may  the  solution  be  known  to  contain  oxide  of  iron  ? 


176  CHEMISTRY. 

lime,  which  must  be  collected  on  a  filter,  dried  at  a  heat  helow 
that  of  redness,  and  afterwards  weighed.  The  remain! ng  fluid 
must  be  boiled  for  a  quarter  of  an  hour,  when  the  magnesia,  if 
there  be  any,  will  be  precipitated  combined  with  carbonic  acid  ; 
and  its  quantity  must  be  ascertained  in  the  same  manner  as  that 
of  the  carbonate  of  lime.  If  any  minute  proportion  of  alumina 
should,  from  peculiar  circumstances,  be  dissolved  by  the  acid,  it 
will  be  found  in  the  precipitate  with  the  carbonate  of  lime,  and  it 
may  be  separated  from  it  by  boiling  for  a  few  minutes  with  soap 
lye  sufficient  to  cover  the  solid  matter :  for  this  lye  dissolves 
alumina,  without  acting  upon  carbonate  of  lime. 

488.  (7.)  The  quantity  of  insoluble  animal  and  vegetable  mat- 
ter may  next  be  ascertained  with  sufficient  precision,  by  heating 
it  to  a  strong  red   heat  in  a  crucible  over  a  common  fire,  till  no 
blackness  remains  in  the  mass,  stirring  it  frequently  meanwhile 
with  a  metallic  wire.     The  loss   of  weight  will   ascertain  the 
quantity  of  animal  and  vegetable  matter  there  was,  but  not  the 
proportions  of  each.     If  the  smell  emitted,  during  this  process, 
resemble  that  of  burnt  feathers,  it  is  a  certain  indication  of  the 
presence  of  some  animal  matter;  and  a  copious  blue  flame  almost 
always  denotes  a  considerable  proportion  of  vegetable  matter. 
Nitrate  of  ammonia,  in  the  proportion  of  twenty  grains  to  a 
hundred  of  the  residuum  of  the  soil,  will  greatly  accelerate  this 
process — if  the  operator  be  in  haste — and  not  affect  the  result,  as 
it  will  be  decomposed  and  evaporate. 

489.  (8.)  What  remains  after  this  decomposition  of  the  vege- 
table and  animal  matter,  consists  generally  of  minute  particles  of 
earthy  matter,  which  are  usually  a  mixture  of  alumina  and  silex 
with  oxide  of  iron.     To  separate  these,  boil  them  two  or  three 
hours  in  sulphuric  acid  diluted  with  four  times  its  weight  of 
water,  allowing  a  hundred  and  twenty  grains  of  acid  for  every 
hundred  grains  of  the  residuum. 

Mineral  Waters. 

490.  The  examination  of  mineral  waters,  with  a  view  to  acer- 
tain  their  ingredients,  and  thence  their  medicinal  qualities,  and 
the  means  of  compounding  them  artificially,  is  an  object  of  con- 
siderable importance  to  society.     It  is  likewise  a  subject  which 
deserves  to  be  attended  to,  because  it  affords  no  mean  opportunity 
for  the  agreeable  practice  of  chemical  skill.     But  this  investiga- 
tion is  more  especially  of  importance  to  the  daily  purposes  of 
life,  and  the  success  of  manufactures.     It  cannot  but  be  an  inte- 
resting object,  to  ascertain  the  component  parts  and  qualities  of  the 

By  what  reagent  will  the  carbonate  of  lime  be  precipitated? 

How  the  carbonate  of  magnesia? 

How  are  the  insoluble  ingredients  ascertained  to  contain  animal  mat- 
ter? 

How  shall  we  be  informed  of  the  presence  of  vegetable  ingredients? 

What  circumstances  render  important  the  knowledge  of  the  composition 
of  mineral  waters  ? 


MINERAL  WATERS.  177 

waters  daily  consumed  by  the  inhabitants  of  large  towns  and 
vicinities.  A  very  minute  portion  of  unwholesome  matter,  daily 
taken,  may  constitute  the  principal  cause  of  the  differences  in 
salubrity  which  are  observable  in  different  places.  And  with  re- 
gard to  manufactures,  it  is  well  known  to  the  brewer,  the  paper- 
maker,  the  bleacher,  and  a  variety  of  other  artists,  of  how  much 
consequence  it  is  to  them,  that  this  fluid  should  either  be  pure,  or 
at  least  not  contaminated  with  such  principles  as  tend  to  injure 
the  qualities  of  the  articles  they  make. 

491.  The  topography  of  the  place  where  these  waters  rise  is 
the  first  thing  to  be  considered.     By  examining  the  ooze  formed 
by  them,  and  the  earth  or  stones  through  which  they  are  strained 
and  filtered,  some  judgment  may  be  formed  of  their  contents.     In 
filtering  through  the  earth,  and  meandering  on  its  surface,  they 
take  with  them  particles  of  various  kinds,  which  their  extreme 
attenuation  renders  capable  of  being  suspended  in  the  fluid  that 
serve's  for  their  vehicle.    Hence  we  shall  sometimes  find  in  these 
waters,  siliceous,  calcareous,  or  argillaceous  earth;  and  at  other 
times,  though  less  frequently,  sulphur,  magnesian  earth,  or,  from 
the  decomposition  of  carbonated  iron,  ochre. 

492.  The  following  are  the  ingredients  that  may  occur  in  mine- 
ral waters : — 

(1.)  The  gases  found  are  common  air,  oxygen,  hydrogen,  and 
sulphuretted  hydrogen.  (2.)  The  acids,  uncombined,  are  the 
carbonic,  sulphuric,  and  boracic.  (3.)  The  only  free  alkali  is 
soda  and  the  free  earths,  silex  and  lime.  (4.)  The  only  salts  are 
sulphates,  nitrates,  muriates,  carbonates,  and  borates. 

493.  The  testing  of  mineral  waters  consists — (1.)  In  the  exami- 
nation of  them  by  the  senses  :  (2.)  In  the  examination  of  them  by 
reagents. 

The  examination  by  the  senses  consists  in  observing  the  effect 
of  the  water,  as  to  appearance,  smell,  and  taste. 

The  appearance  of  the  water,  the  instant  in  which  it  is  pumped 
out  of  the  well,  as  well  as  after  it  has  stood  for  some  time,  affords 
several  indications,  from  which  we  are  enabled  to  form  a  judgment 
concerning  its  contents.  If  the  water  be  turbid  at  the  well,  the 
substances  are  suspended  only,  and  not  dissolved  ;  but  if  the  water 
be  clear  and  transparent  at  the  well,  and  sometime  intervenes  be- 
fore it  becomes  turbid,  the  contents  are  dissolved  by  means  of 
carbonic  acid. 

494.  The  presence  of  this  gas  is  likewise  indicated  by  small 
bubbles,  that  rise  from  the  bottom  of  the  well,  and  burst  in  the 
air  while  they  are  making  their  escape,  though  the  water  at  the 
same  time  perhaps  has  not  an  acid  taste.     But  the  most  evident 

To  what  branch  of  manufactures  is  the  subject  particularly  related  ? 

What  is  the  first  point  to  be  considered  ? 

Why? 

What  four  classes  of  substances  exist  in  mineral  waters  ? 

In  what  two  methods  may  we  test  the  character  of  mineral  waters  ? 

How  may  we  judge  of  the  ingredients  in  water  by  the  eye  ? 


178  CHEMISTRY. 

proof  of  a  spring  containing  carbonic  acid,  is  the  generation  of 
bubbles,  on  the  water  being  shaken,  and  their  bursting  with  more 
or  less  noise,  while  the  air  is  making  its  escape. 

495.  The  sediment  deposited  by  the  water  in  the  well  is  like- 
wise to  be  examined  : — if  it  be  yellow,  it  indicates  the  presence 
of  iron ;  if  black,  that  of  iron  combined  with  sulphur ;  but  cha- 
lybeate waters  being  seldom  sulphuretted,  the  latter  occurs  very 
rarely.     As  to  the  colour  of  the  water  itself,  there  are  few  in- 
stances where  this  can  give  any  indication  of  its  contents,  as 
there  are  not  many  substances  that  colour  it.     The  odour  of  the 
water  serves  chiefly  to  discover  the  presence  of  sulphuretted  hy- 
drogen in  it;  such  waters  as  contain  this  substance  have  a  pecu- 
liar fetid  smell,  somewhat  resembling  rotten  eggs. 

496.  The  taste  of  a  spring,  provided  it  be  perfectly  ascertained 
by  repeated  trials,  may  afford  some  useful  indications  with  respect 
to  the  contents.     It  may  be  made  very  sensible  by  tasting  water 
in  which  the  various  salts  that  are  usually  found  in  such  waters 
are  dissolved  in  various  proportions.     There  is  no  certain  depen- 
dence, however,  to  be  placed  on  this  mode  of  investigation  ;  for  in 
many  springs  the  taste  of  sulphate  of  soda  is  disguised  by  that  of 
the  sea  salt  united  with  it.     The  water,  too,  is  not  only  to  be 
tasted  at  the  spring,  but  after  it  has  stood  for  some  time.    This  pre- 
caution must  be  particularly  observed  with  respect  to  such  waters 
as  are  impregnated  with  carbonic  acid  ;  for  the  other  substances 
contained  in  them  make  no  impression  on  the  tongue,  till  the  car- 
bonic acid  has  made  its  escape ;  and  it  is  for  the  same  reason  that 
these  waters  must  be  evaporated  in  part,  and  then  tasted  again. 

497.  Though  the  specific  gravity  of  any  water  contributes  but 
very  little  towards  determining  its  contents,  still  it  may  not  be 
entirely  useless  to  know  the  specific  wreifjht  of  the  water,  the 
situation  of  the  spring,  and  the  kind  of  sediment  deposited  by  it. 

498.  The  examination  of  the  water  by  means  of  reagents  shows 
what  they  contain,  but  not  how  much  of  each  principle.    In  many 
instances  this  is  as  much  as  the  inquiry  demands  ;  and  it  is  always 
of  use  to  direct  the  proceedings  in  the  proper  analysis. 

It  is  absolutely  necessary  to  make  the  experiment  with  water 
just  taken  up  from  the  spring,  and  afterward  with  such  as  has 
been  exposed  for  some  hours  to  the  open  air ;  and  sometimes  a 
third  essay  is  to  be  made  with  a  portion  of  the  water  that  has 
been  boiled  and  afterward  filtered.  If  the  water  contain  but  few 
saline  particles,  it  must  be  evaporated  ;  as  even  the  most  sensible 
reagents  do  riot  in  the  least  affect  it,  if  the  salts,  the  presence  of 
which  is  to  be  discovered  by  them,  are  diluted  with  too  great  a 
quantity  of  water.  Now,  it  may  happen,  that  a  water  shall  be 

How  is  the  presence  of  carbonic  acid  best  ascertained  ? 

What  judgment  may  we  form  of  water  from  the  appearance  of  its  sedi- 
ment? 

What  kind  of  materials  may  the  sense  of  smell  help  us  to  detect  ? 

At  what  period  may  we  rely  on  the  sense  of  taste  to  indicate  the  cha- 
racter of  water  ? 


MINERAL  WATERS.  179 

impregnated  with  a  considerable  number  of  saline  particles  of  dif- 
ferent kinds,  though  some  of  them  may  be  present  in  too  small  a 
quantity ;  for  which  reason  the  water  must  be  examined  a  second 
time,  after  having  been  boiled  down  to  three-fourths. 

499.  The  substances  of  which  the  presence  is  discoverable  by 
reagents  are: — 

Carbonic  acid.  When  this  is  not  combined  with  any  base,  or 
not  with  sufficient  to  neutralize  it,  the  addition  of  lime  water  will 
throw  down  a  precipitate  soluble  with  effervescence  in  muriatic 
acid.  The  infusion  of  litmus  is  reddened  by  it;  but  the  red  colour 
gradually  disappears,  and  may  be  again  restored  by  the  addition 
of  more  of  the  mineral  water.  When  boiled,  it  loses  the  property 
of  reddening  the  infusion  of  litmus.  According  to  Pfaff,  the  most 
sensible  test  of  this  acid  is  acetate  of  lead. 

500.  The  mineral  acids,  when  present  uncombined  in  water, 
give  the  infusion  of  litmus  a  permanent  red,  even  though  the  water 
has  been  boiled.     Bergmann  has  shown  that  paper,  stained  with 
litmus,  is  reddened  when  dipped  into  water  containing  3^1  °f 
sulphuric  acid. 

Water  containing  sulphuretted  hydrogen  gas  is  distinguished  by 
the  following  properties : — It  exhales  the  peculiar  odour  of  sul- 
phuretted hydrogen  gas.  It  reddens  the  infusion  of  litmus  fuga- 
ciously.  It  blackens  paper  dipped  into  a  solution  of  lead,  and 
precipitates  the  nitrate  of  silver  black  or  brown. 

501.  Alkalies,  and  alkaline  and  earthy  carbonates,  are  distinguished 
by  the  following  tests  : — The  infusion  of  turmeric,  or  paper  stained 
with  turmeric,  is  rendered  brown  by  alkalis;  or  reddish-brown,  if 
the  quantity  be  minute.     This  change  is  produced  when  the  soda 
in  water  amounts  only  to  -^  TTT  Part-     Paper  stained  with  brasil 
wood,  or  the  infusion  of  brasil  wood,  is  rendered  blue ;  but  this 
change  is  produced  also  by  the  alkaline  and  earthy  carbonates. 
Bergmann  ascertained  that  water  containing  j-^-^j  part  of  carbonate 
of  soda  reddens  paper,  stained  with  brasil  wood,  blue.     Litmus 
paper,  reddened  by  vinegar,  is  restored  to  its  original  blue  colour. 
This  change  is  produced  by  the  alkaline  and  earthy  carbonates 
also.     When  these  changes  are  fugacious,  we  may  conclude  that 
the  alkali  is  ammonia. 

502.  Fixed  alkalies  exist  in  water  that  occasions  a  precipitate 
with  muriate  of  magnesia  after  being  boiled.    Volatile  alkali  may 
be  distinguished  by  the  smell ;  or  it  may  be  obtained  in  the  re- 
ceiver by  distilling  a  portion  of  the  water  gently,  and  then  it  may 
be  distinguished  by  the  above  tests. 

Earthy  and  metallic  carbonates  are  precipitated  by  boiling  the 
water  containing  them  ;  except  carbonate  of  magnesia,  which  is 
precipitated  but  imperfectly. 

How  shall  we  be  able  to  detect  the   presence  of  an  ingredient  which 
originally  constitutes  but  a  very  small  portion  of  the  water  ? 
What  is  the  test  of  carbonic  acid  ? 
What  is  that  of  the  mineral  acids  ? 
How  is  sulphuretted  hydrogen  detected  ? 
What  tests  show  the  presence  of  alkalis  and  earthy  carbonates  ? 


180  CHEMISTRY. 

503.  Iron  is  discovered  by  the  following  tests : — The  addition 
of  tincture  of  galls  gives  water,  containing  iron,  a  purple  or  black 
colour.     This  test  indicates  the  presence  of  a  very  minute  portion 
of  iron.    If  the  tincture  have  no  effect  upon  the  water,  after  boiling, 
though  it  colours  it  before,  the  iron  is  in  a  state  of  a  carbonate.  The 
following  observations  of  Westrumb  on  the  colour  which  iron 
gives  to  galls,  as  modified  by  other  bodies,  deserves  attention.    A 
violet  indicates  an  alkaline  carbonate,   or  earthy  salts.      Dark 
purple  indicates  other  alkaline  salts.     Purplish-red  indicates  sul- 
phuretted hydrogen  gas.     Whitish,  and  then  black,  indicates  sul- 
phate of  lime. 

504.  Sulphuric  add  exists  in  waters  that  form  a  precipitate  with 
the  following  solutions : — Muriate,  nitrate,  or  acetate  of  baryta, 
strontia  or  lime,  or  nitrate  or  acetate  of  lead.     Of  these  the  most 
powerful  by  far  is  muriate  of  baryta,  which  is  capable  of  de- 
tecting the  presence  of  sulphuric  acid  uncombined,  when  it  does 
not  exceed  the  millionth  part  of  the  water.     Acetate  of  lead  is 
next  in  point  of  power.     The  muriates  are  more  powerful  than 
the  nitrates.     The  calcareous  salts  are  least  powerful.     All  these 
tests  are  capable  of  indicating  a  much  smaller  proportion  of  un- 
combined sulphuric  acid,  than  when  it  is  combined  with  a  base. 
To  render  muriate  of  baryta  a  certain  test  of  sulphuric  acid,  the 
following  precautions  must  be  observed  : — The  muriate  must  be 
diluted ;  the  alkalis  or  alkaline  carbonates,  if  the  water  contain 
any,  must  be  previously  saturated  with  muriatic  acid  ;  the  preci- 
pitate must  be  insoluble  in  muriatic  acid  ;  if  boracic  acid  be  sus- 
pected, muriate  of  strontia  must  be  tried,  which  is  not  precipitated 
by  boracic  acid.     The  hydrosulphurets  precipitate  barytic  solu- 
tions ;  but  their  presence  is  easily  discovered  by  the  smell. 

505.  Muriatic  acid  is  detected  by  nitrate  of  silver,  which  occa- 
sions a  white  precipitate,  or  a  cloud,  in   water  containing  an 
exceedingly  minute  portion  of  this  acid.     To  render  this  test  cer- 
tain, the  following  precautions  are  necessary : — The  alkalis  or 
carbonates  must  be  previously  saturated  with  nitric  acid.     Sul- 
phuric acid,  if  any  be  present,  must  be  previously  removed  by 
means  of  nitrate  of  baryta.     The  precipitate  must  be  insoluble  in 
nitric  acid.     Pfaff  says,  that  the  mild  nitrate  of  mercury  is  the 
most  sensible  test  of  muriatic  acid  ;  and  that  the  precipitate  is  not 
soluble  in  an  excess  of  any  acid. 

506.  Boracic  acid  is  detected  by  means  of  acetate  of  lead,  with 
which  it  forms  a  precipitate  insoluble  in  acetic  acid.     But  to  ren- 
der this  test  certain,  the  alkalies  and  earths  must  be  previously 
saturated  with  acetic  acid,  and  the  sulphuric  and  muriatic  acids 
removed  by  means  of  acetate  of  strontia  and  acetate  of  silver. 

What  test  proves  the  presence  of  iron  ? 

What  rule  will  enable  us  to  judge  what  compound  of  iron  is  present  in 
water  ? 

What  is  the  test  for  sulphuric  acid  ? 
What  will  prove  the  presence  of  muriatic  acid  ? 
What  of  boracic  acid  ? 


MINERAL  WATERS.  181 

Baryta  is  detected  by  the  insoluble  white  precipitate  which  it 
forms  with  diluted  sulphuric  acid. 

507.  Lime  is  detected  by  means  of  oxalic  acid,  which  occasions 
a  white  precipitate  in  water  containing  a  very  minute  proportion 
of  this  earth.     To  render  this  test  decisive,  the  following  pre- 
cautions are  necessary: — The  mineral  acids,  if  any  be  present, 
must  be  previously  saturated  with  an  alkali.     Baryta,  if  any  be 
present,  must  be  previously  removed  by  means  of  sulphuric  acid. 
Oxalic  acid  precipitates  magnesia  but  very  slowly,  whereas  it 
precipitates  lime  instantly. 

508.  Magnesia  and  alumina.     The  presence  of  these  earths  is 
ascertained  by  the  following  tests : — -Pure  ammonia  precipitates 
them  both,  and  no  other  earth,  provided  the  carbonic  acid  have 
been  previously  separated  by  a  fixed  alkali  and  boiling.     Lime- 
water  precipitates  only  these  two  earths,  provided  the  carbonic 
acid  be  previously  removed,  and  the  sulphuric  acid  also,  by  means 
of  nitrate  of  baryta. 

The  alumina  may  be  separated  from  the  magnesia,  after  both 
have  been  precipitated  together,  either  by  boiling  the  precipitate 
in  caustic  potash,  which  dissolves  the  alumina  and  leaves  the 
magnesia ;  or  the  precipitate  may  be  dissolved  in  muriatic  acid, 
precipitated  by  an  alkaline  carbonate,  dried  in  the  temperature  of 
100  degrees,  and  then  exposed  to  the  action  of  diluted  muriatic 
acid,  which  dissolves  the  magnesia  without  touching  the  alu- 
mina. 

509.  Sllex  may  be  ascertained  by  evaporating  a  portion  of  water 
to  dryness,  and  redissolving  the  precipitate  in  muriatic  acid.    The 
silex  remains  behind  undissolved. 

By  these  means  we  may  detect  the  presence  of  the  different 
substances  commonly  found  in  waters ;  but  as  they  are  generally 
combined  so  ^s  to  form  salts,  it  is  necessary  we  should  know 
what  these  combinations  are.  This  is  a  more  difficult  task, 
which  Mr.  Kirwan  teaches  us  to  accomplish  by  the  following 
methods : 

510.  (1.)  To  ascertain  the  presence  of  the  different  sulphates. 
The  sulphates  which  occur  in  water  are  seven ;  but  one  of  these, 

namely,  sulphate  of  copper,  is  so  uncommon,  that  it  may  be  excluded 
altogether.  The  same  remark  applies  to  sulphate  of  ammonia.  It 
is  almost  unnecessary  to  observe,  that  no  sulphate  need  be  looked 
for,  unless  both  its  acid  and  base  have  been  previously  detected 
in  the  water. 

541.  Sulphate  of  soda  may  be  detected  by  the  following 
method  : — Free  the  water  to  be  examined  of  all  earthy  sulphates, 
by  evaporating  it  to  one-half,  and  adding  lime-water  as  long  as 

What  will  prove  the  presence  of  baryta  ? 
What  of  lime? 

How  are  we  to  know  whether  magnesia  and  alumina  are  contained  in 
mineral  water? 

What  method  separates  the  silex  if  any  be  present  ? 

Q 


182  CHEMISTRY. 

any  precipitate  appears.  By  these  means  the  earths  will  all  be 
precipitated  except  lime,  and  the  only  remaining  earthy  sulphate 
will  be  the  sulphate  of  lime,  which  will  be  separated  by  evapo- 
rating the  liquid  till  it  becomes  concentrated,  and  then  dropping  into 
it  a  little  alcohol,  and,  after  filtration,  adding  a  little  oxalic  acid. 

512.  With  the  water  thus  purified,  mix  solution  of  lime.     If  a 
precipitate  appear,  either  immediately,  or  on  the  addition  of  a  little 
alcohol,  it  is  a  proof  that  sulphate  of  potash  or  of  soda  is  present. 
Which  of  the  two  may  be  determined,  by  mixing  some  of  the 
purified  water  with  acetate  of  baryta.     Sulphate  of  baryta  preci- 
pitates.    Filter  and  evaporate  to  dryness.     Digest  the  residuum 
in  alcohol.     It  will  dissolve  the  alkaline  acetate.     Evaporate  to 
dryness,  and  the  dry  salt  will  deliquesce  if  it  be  acetate  of  potash, 
but  effloresce  if  it  be  acetate  of  soda. 

513.  Sulphate  of  lime  may  be  detected  by  evaporating  the 
water  suspected  to  contain  it    to  a  few  ounces.     A  precipitate 
appears,  wrhich,  if  it  be  sulphate  of  lime,  is  soluble  in  500  parts 
of  water,  and  the  solution  affords  a  precipitate  with  the  muriate 
of  baryta,  oxalic  acid,  carbonate  of  magnesia,  and  alcohol. 

514.  Alum  may  be  detected  by  mixing  carbonate  of  lime  with 
the  water  suspected  to  contain  it.     If  a  precipitate  appear,  it  in- 
dicates the  presence  of  alum,  or  at  least  of  sulphate  of  alumina ; 
provided  the  water  contains  no  muriate  of  baryta  or  metallic  sul- 
phates.   The  first  of  these  salts  is  incompatible  with  alum ;  the 
second  may  be  removed  by  the  alkaline  pmssiates.    When  a  pre- 
cipitate is  produced  in  water  by  muriate  of  lime,  carbonate  of 
lime,  and  muriate  of  magnesia,  we  may  conclude  that  it  contains 
alum  or  sulphate  of  alumina. 

515.  Sulphate  of  magnesia  may  be  detected  by  means  of  hy- 
drosulphuret  of  strontia,  which  occasions  an  immediate  precipitate 
with  this  salt,  and  with  no  other ;  provided  the  water  be  pre- 
viously deprived  of  alum,  if  any  be  present,  by  means  of  carbo- 
nate of  lime,  and  provided  also  that  it  contains  no  uncombined  acid. 

Sulphate  of  iron  is  precipitated  from  water  by  alcohol,  and  then 
it  may  be  easily  recognised  by  its  properties. 

516.  (2.)  To  ascertain  the  presence  of  the  different  muriates. 
The  muriates  found  in  waters  amount  to  eight,  or  to  nine,  if 

muriate  of  iron  be  included.  The  most  common  by  far  is  muriate 
of  soda. 

Muriate  of  soda  and  of  potash  may  be  detected  by  the  following 
method  : — Separate  the  sulphuric  acid  by  alcohol  and  nitrate  of 
baryta.  Decompose  the  earthy  nitrates  and  muriates  by  adding 
sulphuric  acid.  Expel  the  excess  of  muriatic  and  nitric  acids  by 
heat.  Separate  the  sulphates  thus  formed  by  alcohol  and  baryta 
water.  The  water  thus  purified  can  contain  nothing  but  alkaline 
nitrates  and  muriates.  If  it  form  a  precipitate  with  acetate  of 
silver,  we  may  conclude  that  it  contains  muriate  of  soda  or  of 

How  shall  the  presence  of  sulphate  of  soda  be  known  ? — sulphate  oflime  ? 
— of  alumina  ? — of  magnesia  ? — of  iron? 


$ 


MINERAL  WATERS.  183 

potash.  To  ascertain  which,  evaporate  the  liquid  thus  preci- 
pitated to  dry  ness.  Dissolve  the  acetate  in  alcohol,  and  again 
evaporate  to  dryness.  The  salt  will  deliquesce,  if  it  be  acetate 
of  potash,  but  effloresce  if  it  be  acetate  of  soda. 

517.  The  potash  salts  are  most  readily  distinguished  by  the 
precipitate  which  they  afford  to  muriate  of  platinum,  which  the 
soda  salts  do  not  occasion. 

Muriate  of  baryta  may  be  detected  by  sulphuric  acid,  as  it  is 
the  only  barytic  salt  hitherto  found  in  water. 

Muriate  of  lime  may  be  detected  by  the  following  method  : — 
Free  the  water  from  sulphate  of  lime  and  other  sulphates,  by 
evaporating  it  to  a  few  ounces,  mixing  it  with  alcohol,  and  adding 
last  of  all  nitrate  of  baryta  as  long  as  any  precipitate  appears. 
Filter  the  water,  evaporate  to  dryness ;  treat  the  dry  mass  with 
alcohol ;  evaporate  the  alcohol  to  dryness ;  and  dissolve  the  re- 
siduum in  water.  If  this  solution  give  a  precipitate  with  acetate 
of  silver  and  oxalic  acid,  it  may  contain  muriate  of  lime.  It  must 
contain  it  in  that  case,  if,  after  being  treated  with  carbonate  of 
lime,  it  give  no  precipitate  with  ammonia.  If  the  liquid  in  the 
receiver  give  a  precipitate  with  nitrate  of  silver,  muriate  of  lime 
existed  in  the  water. 

518.  Muriate  of  magnesia  may  be  detected  by  separating  all 
the  sulphuric  acid  by  means  of  nitrate  of  baryta.   Filter,  evaporate 
to  dryness,  and  treat  the  dry  mass  with  alcohol.     Evaporate  the 
alcoholic  solution  to  dryness,  and  dissolve  the  residuum  in  water. 
The  muriate  of  magnesia,  if  the  water  contained  any,  will  be 
found  in  this  solution.    Let  us  suppose,  that,  by  the  tests  formerly 
described,  the  presence  of  muriatic  acid  and  of  magnesia,  in  this 
solution,  has  been  ascertained.     In  that  case,  if  carbonate  of  lime 
afford  no  precipitate,  and  if  sulphuric  acid  and  evaporation,  to- 
gether with  the  addition  of  a  little  alcohol,  occasion  no  precipi- 
tate, the  solution  contains  only  muriate  of  magnesia.     If  these 
tests  give  precipitates,  we  must  separate  the  lime  which  is  present 
by  sulphuric  acid  and  alcohol,  and  distil  off  the  acid  with  which 
it  was  combined.     Then  the   magnesia  is  to  be  separated   by 
oxalic  acid  and  alcohol,  and  the  acid  with  which  it  was  united  is 
to  be  distilled  off.     If  the  liquid  in  the  retort  give  a  precipitate 
with  nitrate  of  silver,  the  water  contains  muriate  of  magnesia. 

519.  Muriate  of  alumina  may  be  discovered  by  saturating  the 
water,  if  it  contain  an  excess  of  alkali,  with  nitric  acid,  and  by 
separating  the  sulphuric  acid  by  means  of  nitrate  of  baryta.     If 
the  liquid,  thus  purified,  give  a  precipitate  with  carbonate  of  lime, 
it  contains  muriate  of  alumina.     The  muriate  of  iron,  or  of  man- 
ganese, if  any  be  present,  is  also  decomposed,  and  the  iron  pre- 
cipitated by  this  salt. 

520.  Such  are  the  methods  by  which  the  presence  of  the  dif- 
ferent saline  contents  of  waters  may  be  ascertained.     The  labour 

How  shall  we  proceed  to  find  whether  water  contains  muriate  of  soda  or 
of  potash  ? — muriate  of  baryta  ? — of  lime  ? — of  magnesia  ? — of  alumina  ? 


1  84  CHEMISTRY. 

of  analysis  may  be  considerably  shortened  by  observing,  that  the 
following  salts  are  incompatible  with  each  other,  and  cannot  exist 
together  in  water,  except  in  very  minute  proportion  :  — 
Salts.  Incompatible  with 

Fixed  alkaline  sulphates  J"  ^itr.ate  offl™e  and,magnesia' 
£  Muriate  of  lime  and  magnesia. 

r  Alkalies, 
Sulphate  of  lime      .     .     <  Carbonate  of  magnesia, 

C  Muriate  of  baryta. 

("Alkalies, 
Alum  J  Muriate  of  baryta, 

j  Nitrate,  muriate,  carbonate  of  lime, 

(_Carbonate  of  magnesia. 

r  Alkalies, 
Sulphate  of  magnesia   .     <  Muriate  of  baryta, 

C.  Nitrate  and  muriate  of  lime. 

r  Alkalies, 
Sulphate  of  iron       .     .     <  Muriate  of  baryta, 

C  Earthy  carbonates. 

r  Sulphates, 
Muriate  of  baryta    .     .     <  Alkaline  carbonates, 

C  Earthy  carbonates. 

("Sulphates,  except  of  lime, 
Muriate  of  lime        .     .     <  Alkaline  carbonates, 

C.  Earthy  carbonates. 


Muriate  of  magnesia    . 

r  Alkaline  carbonates, 

Nitrate  of  lime    .     .     .     <  Carbonate  of  magnesia  and  alumina, 
C.  Sulphates,  except  of  lime. 

521.  Beside  the  substances  above  described,  there  is  sometimes 
found  in  water  a  quantity  of  bitumen  combined  with  alkali,  and 
in  the  state  of  soap.    In  such  waters,  acids  occasion  a  coagulation  ; 
and  the  coagulum  collected  on  a  filter  discovers  its  bituminous 
nature  by  its  combustibility. 

522.  Water  also  sometimes  contains  extractive  matter;   the 
presence  of  which  may  be  detected  by  means  of  nitrate  of  silver. 
The  water  suspected  to  contain  it,  must  be  freed  from  sulphuric 
and  nitric  acid  by  means  of  nitrate  of  lead  ;  after  this,  if  it  give 
a  brown  precipitate  with  nitrate  of  silver,  we  may  conclude  that 
extractive  matter  is  present. 

How  may  the  labour  of  analysis  be  often  abridged  ? 

What  substances  are  incompatible  in  mineral  water  with  fixed  alkaline 
sulphates?  —  with  sulphate  of  lime?  —  with  alum?  —  with  sulphate  of  mag- 
nesia ?  —  with  sulphate  of  iron  ?  —  with  muriate  of  baryta  ?  —  of  lime  ?  —  of 
magnesia  ?  —  with  nitrate  of  lime  ? 

How  is  the  presence  of  bitumen  detected  ? 

How  that  of  extractive  matter? 


MINERAL  WATERS.  185 


Works  in  the  Department  of  Chemistry. 

In  this  and  the  other  lists  of  works  appended  to  the  several 
treatises  contained  in  the  Scientific  Class  Books,  the  works  first 
named  are,  in  general,  those  supposed  to  be  most  easily  procured 
by  the  student,  and  they  are  commonly  the  most  familiar  and 
popular  in  their  modes  of  treating  their  respective  subjects.  The 
latter  titles  in  each  list  are  those  of  works  supposed  to  be  met 
with  principally  in  public  libraries. 

Turner's  Chemistry,  new  edition,  by  Dr.  Franklin  Bache. 
Philadelphia.  1835. 

Webster's  Manual  of  Chemistry,  on  the  Basis  of  Brande's, 
1  vol.  8vo. 

Henry's  Chemistry,  2  vols.  8vo.    Philadelphia. 

Farraday's  Chemical  Manipulations,  edited  by  Dr.  J.  K.  Mit- 
chell. Philad.  1  vol.  8vo. 

Dr.  Hare's  Compendium  of  Illustrations  in  Chemistry,  &c.  1 
vol.  8vo. 

Ure's  Chemical  Dictionary.    1  vol.  8vo. 

Porter's  Chemistry  of  the  Arts,  on  the  Basis  of  Gray's  Operative 
Chemist.  Philad.  1  vol.  8vo. 

Silliman's  American  Journal  of  Science,  passim. 

Transactions  of  the  British  Association. 

Berzelius's  Chemistry.  Paris  edition. 

Annales  de  Chemie  et  de  Physique. 


METALLURGY. 

1.  THE  term  metallurgy  in  its  most  extensive  signification,  de- 
notes the  working  of  metals,  and  may  thus  include  all  operations 
connected  with  the  raising  of  metallic  ores  from  mines,  or  procuring 
them  from  metalliferous  sands ;  those  employed  for  ascertaining  the 
value  of  minerals  whence  metals  are  obtained;  the  multifarious 
processes  relative  to  the  extraction  of  the  various  metals  from  their 
respective  ores ;  and  the  still  more  numerous  processes  which  relate 
to  manufactures  of  hardware,  steel,  tin-plate,  brass,  bronze,  gold 
and  silver  plate,  as  well  as  of  other  metals  and  their  combinations. 
But  metallurgy  in  a  more  restricted  sense,  is  to  be  regarded  as  a 
department  of  chemistry,  comprising  the  description  and  rationale 
of  those  chemical  operations  by  means  of  which  the  useful 
metals  and  their  alloys  are  separated  from  the  saline,  earthy,  or 
stony  substances  in  conjunction  with  which  they  are  presented  to 
us  by  nature. ^Under  this  point  of  view  the  subject  will  be  treated 
in  the  following  pages;  but  some  preliminary  notices  of  metallic 
veins,  mines,  and  the  art  of  mining,  may  be  introduced,  as  being 
both  interesting  and  instructive,  tending  to  illustrate  the  proper- 
ties and  composition  of  those  substances  to  which  the  attention  of 
the  metallurgist  or  metallurgic  chemist  is  principally  directed. 
Docimasties,  or  the  art  of  assaying,  as  a  process  preceding  the 

reduction  of  metals,  will  also  demand  our  attention.  , 

/ 

Mineral  Deposits  and  Mines. 

2.  Nature  presents  metallic  substances  to  our  notice  scattered 
on  the  surface  or  inclosed  within  the  crust  of  the  terrestial  globe, 
cither  in  a  state  of  purity,  or  in  combination  with  various  other  bo- 
dies.  These  combinations  are  properly  termed  mineralized  metals, 
or  ores;  metals  in  this  state  being  united  to  extraneous  matter, 
which  alters  their  properties  in  such  a  manner,  that  their  real  nature 
can  only  be  ascertained  by  chemical  analysis.    Sometimes  two  or 
more  metals  are  combined  with  the    same  mineralizing  body ; 
frequently  a  single  metal  is  united  with  several  such  bodies,  and 
yet  more  frequently,  in  mines,  are  found  combinations  consisting 
of  several  metals  and  various  mineralizing  bodies  united  together. 

3.  A  few  only  of  the  metals  (almost  exclusively  those  which 
are  termed  precious  metals)  are  found  in  a  state  of  purity  dis- 
persed through  the  soil  of  valleys,  or  mixed  with  the  sand  of 

What  is  the  origin  and  use  of  the  term  metallurgy  ? 

What  may  it  include  in  its  most  extensive  sense? 

What  is  its  most  restricted  meaning  ? 

What  is  meant  by  docimastics  ? 

In  what  states  are  metallic  substances  found  in  nature  ? 

*  From  the  Greek  MeraXAov,  metal,  and  vEoypv,  work. 

186 


MINERAL  BEDS.  187 

rivers,  or  with  earthy  matter  deposited  by  mountain  torrents.  It 
is  thus  that  gold  and  platina,  and  especially  the  former,  frequently 
occur  in  masses,  often  minute,  sometimes  of  several  pounds 
weight,  and  at  all  intermediate  sizes,  in  alluvial  soil,  from  which 
the  metal  is  separated  principally  by  mechanical  means.  Both 
metallic  ores  and  native  metals  are  occasionally  disseminated  in 
grains  through  rocks,  and  when  they  are  thus  found  in  abundance, 
the  whole  mass  of  the  rock  is  worked  as  a  mine  ;  but  this  is  com- 
paratively seldom  the  case.  V  Tinstone,  or  the  oxide  of  tin,  is 
sometimes  thus  dispersed  through  the  substance  of  granitic  rocks 
in  Cornwall,  but  this  is  generally  observed  in  the  vicinity  of  veins 
of  tin  ore.?  This  metal  is  likewise  found  in  alluvial  soil,  in  small 
nodular  masses  of  considerable  specific  gravity,  called  stream-tin 
from  the  manner  in  which  it  is  procured,-by  washing  the  metallife- 
rous sand. 

4.\.Mineral  deposits,  however,  more  usually  occur  in  subterrane- 
ous beds  or  veins.-*  (Metallic  ores  of  some  kinds  form  regular 
strata,  or  mineral  beds,  in  secondary  rocks,  or  in  the  more  ancient 
transition  and  primary  rocks.".  These  beds  are  in  general  horizon- 
tal, but  they  are  sometimes  observed  to  be  highly  inclined,  and 
such  strata  have  been  mistaken  for  veins.  \  The  ores  of  copper, 
iron  and  leadr  are  occasionally  found  in  conjunction  in  beds  in 
primitive  mountains,  sometimes  having  gold  or  silver  intermixed 
with  them.  Cobalt,  and  certain  ores  of  mercury,  likewise  form 
strata.  Iron  ore  is  frequently  found  in  beds  of  great  thickness,  in- 
terposed^ among  rocks  of  gneiss,  mica-slate,  and  clay-slate.  Lead, 
zinc,  manganese,  and  iron  ores  also  occur  abundantly  in  strata  in 
secondary  mountains. 

5.  \When  a  bed  of  metallic  ore  expands  irregularly,  it  sometimes 
forms  masses  of  such  magnitude  as  to  resemble  small  mountains, 
as  is  the  case  with  iron  ore  in  Sweden  and  Norway.  Metallic 
beds,  however,  are  generally  of  limited  extent,  seldom  traversing 
an  entire  mountain,  but  gradually  or  suddenly  terminating  in  a 
thin  edge ;  in  the  language  of  the  miners,  a  stratum  of  ore  is  said 
to  wedge  out.}  Beds  of  minerals  are  not  of  frequent  occurrence  in 
England,  most  of  the  great  deposits  of  metallic  matter  in  that 
country  being  found  in  veins,  as  is  uniformly  the  case  in  the  great 
mining  districts  of  Cornwall,  except  in  the  previously  noted 
stream-works.  Mr.  Bakewell,  however,  alleges  that  beds  of  cop- 
per pyrites  have  been  wrought  in  transition  rocks  in  Cumberland, 

What  varieties  in  the  degree  of  complexity  exist  in  metallic  mine- 
rals? 

What  class  of  the  metals  are  met  with  in  nature  in  a  slate  of  purity  ? 
In  what  situations  do  they  occur? 
In  what  forms  does  the  ore  of  tin  occur  ? 
What  is  the  most  usual  form  of  mineral  deposits? 
How  do  ores  of  copper,  iron,  and  lead  exist  ? 
What  kinds  of  rocks  are  traversed  by  beds  of  iron  ore? 
What  ores  may  be  found  in  strata  in  secondary  mountains  ? 
What  is  meant  by  wedging  out  ? 


188  METALLURGY. 

and  that  the  existence  of  mineral  beds  may  be  suspected  in  other 
counties,  where  they  are  often  confounded  with  veins  by  the  la- 
bouring miners. 

6.  Mineral  veins,  from  their  relative  frequency,  constitute  the 
most  considerable  depositories  of  metallic  matter.    Such  veins  are 
not,  as  may  be  supposed  from  the  general  application  of  the  term, 
tubes  filled  with  metal  or  ore,  but  extended  plates,  or  laminae,  of 
unequal  thickness ;  and  they  differ  most  essentially  from  beds,  in 
that  they  do  not  run  parallel  with  the  direction  of  other  strata,  but 
traverse  or  cross  them  vertically,  or  at  various  degrees  of  inclina- 
tion.    A  vein  may  be  described  as  a  fissure  in  a  rock,  filled  with 
various  substances.     Humboldt  noticed  a  vein  of  calcareous  spar 
140  feet  in  thickness,  traversing  gneiss,  in  the  Alps  of  Switzer- 
land ;  and  Professor  Jameson  mentions  a  vein  of  porphyry  slate, 
nearly  160  feet  wide,  occuring  in  sandstone,  in  the  Isle  of  Arran, 
and  veins  of  pitchstone  and  greenstone,  varying  in  width  from 
ten  to  one  hundred  feet.     But  these  do  not  appear  to  have  been 
of  the  nature  of  metalliferous  veins  which  are  commonly  much 
narrower ;  yet  it  is  said,  that  in  the  silver  mines  of  Pasco,   in 
Peru,  there  is  a  vein  of  brown  ironstone,  containing  silver,  which 
is  1300  yards  in  width. 

7.  When  metallic  ores  are  worked  in  beds,  or  in  veins  of  con- 
siderable thickness,  that  part  of  the  rock  which  covers  the  ore  is 
called  the  roof,  and  that  which  supports  it  the  floor.   These  terms, 
however,  are  principally  applicable  to  mines  worked  in  an  hori- 
zontal direction.     The  metalliferous  veins  of  Cornwall  which  are 
of  most  importance,  namely,  those  producing  tin  and  copper,  ex- 
tend nearly  in  the  direction  of  east  and  west,  with  little  variation. 
Though  there  are  other  veins,  either  destitute  of  metallic  matter, 
or  else  containing  lead  and  silver,  which  chiefly  run  north  and 
south.   The  veins  of  Cornwall  scarcely  ever  descend  vertically,  or 
exactly  at  right  angles  with  the  horizon,  but  almost  always  dip 
from  the  line  of  descent ;  and  this  deviation  from  the  perpendicu- 
lar is  called  by  miners  the  hading  of  the  vein ;  thus  a  vein  may  be 
said  to  hade  or  dip  to  the  north  or  south. 

8.  Metalliferous  veins   in  general  seem  to  observe   no   great 
uniformity  of  direction,  some  descending  almost  perpendicularly, 
and  others  very  obliquely,  in  such  a  manner  that  in  a  single  hill 
instances  may  be  observed  in  which  veins  of  different  descriptions 
dip  or  underlie  in  almost  all  directions,  traversing  each  other  in 
such  a  manner  as  to  defy  the  calculations  of  the  miner.   The  head 
of  a  vein  sometimes  rises  to  the   surface  of  the   soil,  and  may 
thus  be  discovered ;  and  its  existence  is  occasionally  betrayed  by 

To  what  is  the  term  mineral  veins  applied  ? 

In  what  do  they  differ  from  strata  ? 

What  is  meant  by  the  roof  and  what  by  the  floor  of  a  mine  ? 

What  has  been  observed  in  regard  to  the  direction  of  metallic  veins? 

What  is  meant  by  the  hading  of  a  vein  ? 


VEINS.  189 

a  certain  ochraceous  or  rust-like  appearance,  which  may  be  ob- 
served above  its  site,  but  this  is  not  very  common. 

9.  To  what  depth  metallic  veins  may  descend,  has  never  been 
ascertained,  for  no  instance  has  yet  occurred,  of  the  termination  of 
a  vein  being  reached,  though  sometimes  veins  are  found  to  become 
so  thin  and  unproductive  as  not  to  repay  the  labour  of  working 
deeper,  but  more  frequently  the  progress  of  the  miner  is  stopped 
by  water  or  other  obstacles.    Some  of  the  Cornish  mines  are  said 
to  be  nearly  500  yards  in  depth  from  the  surface,  as  the  copper 
and  tin  mine  of  Dolcoath,  which  is  456  yards  deep ;  and  there 
are  several  the  depth  of  which  is  from  300  to  400  yards. 

10.  The  same  vein  sometimes  contains  different  ores  at  different 
depths :    thus  the   ores  of  iron,  copper,  cobalt,  and  silver  are 
found  successively  in  some  of  the  mines  in  Saxony;  and  in  France 
there  are  mines  containing  iron  ore,  below  that  silver  ore,  and  in 
the  lowest  part  copper  ore.     In  Cornwall  sulphuret  of  zinc,  or 
blende,  is  found  abundantly  in  the  upper  part  of  veins,  which  lower 
down  are  rich  in  copper,  and  sometimes  tin  in  the  same  manner 
occurs  in  the  superior  part  of  a  copper  vein. 

11.  The  thickness  of  veins,  as  already  observed,  is  extremely 
variable,  the  same  vein  may  be  in  some  parts  but  a  few  inches 
wide,  and  in  others  extend  to  the  thickness  of  many  feet,  or  even 
yards.     The  vein  at  Dolcoath  mine  varies  from  two  feet  to  forty  ; 
and  in  some  places  is  contracted  to  about  six  inches. 

12.  The  veins,  independent  of  their  extent,  may  be  characterized 
as  rich  or  poor.     In  a  Cornish  mine  called  Whealan  Cotes,  was 
found  a  vein  of  tin  ore  about  three  inches  wide,  yet  so  rich  as  to  be 
worth  working.    Some  of  the  veins  containing  copper,  in  Herland 
mine,  did  not  exceed  six  inches  in  width,  and  after  thus  continuing 
for  a  few  fathoms,  they  passed  away  east  and  west  into  mere 
strings,  or  rather  laminae,  scarcely  thicker  than  paper ;  but  these 
veins  yielded  ore  of  a  rich  quality.     The  thin  veins  or  threads  of 
metallic  matter  which  sometimes  occur  in  working  mines,  may  be 
worth  pursuing,  independent  of  their  product  of  metal,  as  they 
may  lead  to  veins  of  much  greater  thickness,  or  to  bunches,  or 
large  masses  of  metal. 

13.  Veins  are  by  no  means  entirely  filled  with  metalliferous 
matter,  which,  in  fact,  occupies  comparatively  but  a  small  space, 
the  veins  including  minerals  of  different  descriptions.     The  non- 
metalliferous  parts  of  a  vein,  of  whatever  nature  they  may  be,  are 
usually  termed  by  the  miner  deads,  as  being  unproductive  and  use- 

What  is  known  of  the  depth  of  metallic  veins? 

What  facts  have  been  ascertained  in  regard  to  the  situation  of  different 
metallic  ores  in  the  same  mine  ? 

What  degree  of  uniformity  in  regard  to  thickness  characterizes  metallic 
veins  ? 

What  difference  independent  of  direction,  inclination,  depth,  and  thick- 
ness is  it  important  to  consider  in  regard  to  metallic  veins  ? 

To  what  is  the  term  deads  applied  among  miners  ? 


190  METALLURGY. 

less.  Large  empty  spaces  occasionally  occur  in  veins,  but  this  is 
not  often  the  case.  Water  is  found  in  large  quantities  in  mines, 
especially  those  which  are  rich  in  tin  or  copper.  The  sides  of 
metalliferous  veins  are  usually  very  determinate,  being  covered  by 
a  hard,  dark-coloured  incrustation,  called  by  the  miner  the  walls 
of  the  vein  :  and  there  likewise  commonly  runs  down  every  vein 
a  small  seam  of  whitish  clayey  matter,  sometimes  adhering  to  one 
side  of  the  vein,  and  sometimes  to  the  other. 

14.  The  same  substance  which  constitutes  the  incrustation  of 
the  veins,  is  also  often  intermixed  with  the  ore,  forming  with  it 
alternating  layers,  and  with  other  substances  composing  what  is 
called  the  matrix,  gangue,  or  veinstone  of  the  mineral.     Different 
metals  are  accompanied  by  different  kinds  of  gangue,  the  nature 
of  which  may  enable  the  miner  to  form  a  judgment  as  to  the  pro- 
bable value  of  the  vein.     Among  the  substances  thus  found  may 
be  mentioned  quartz,  calcareous  spar,  fluor  spar,  called  in  Derby- 
shire blue  John,   and    sulphate   of  barytes,   also   called   cawk ; 
besides  which,  the  ores  of  one  metal  are  thus  accompanied  by  those 
of  another,  and  frequently  by  pyrites,  (sulphuret  of  iron.)  * 

15.  It  has  been  already  stated  that  in  Cornwall  tin  and  copper 
mines  uniformly  run  in  the  direction  of  east  and  west,  and  that 
other  veins,  extending  north  and  south,  scarcely  ever  contain  a 
trace  of  either  of  those  metals,  being  non-metalliferous,  or  else  af- 
fording the  ores  of  silver,  lead,  cobalt,  or  iron,  or  occasionally 
antimony.  These  north  and  south  veins  are  most  commonly  filled 
by  quartz,  by  a  whitish  or  bluish  argillaceous  substance,  or  by  a 
kind  of  ochre,  and  sometimes  by  all  three.     When  such  a  vein 
meets  with  another  containing  tin  or  copper,  it  passes  through  the 
tin  or  copper  vein  without  interruption,  while  the  latter  becomes 
split,  or  frittered  into  numerous  small  branches,  and  sometimes  its 
contents  seem  to  be  dissipated,  so  that  the  miner  loses  all  traces  of 
the  vein,  or  only  recovers  it  after  a  tedious  search  at  the  distance 
of  perhaps  between  400  and  500  feet.    North  and  south  veins  dif- 
fer greatly  in  breadth,  but  whatever  be  their  dimensions,  they 
always  divide  the  tin  or  copper  veins  which  they  encounter,  and 
generally  alter  the  direction  of  the  latter,  or,  in  the  language  of 
the  miner,  heave  them  out  their  course. 

16.  The  manner  in  which  metalliferous  veins  are  sometimes  in- 
terrupted by  others,  may  be  illustrated  by  the  following  section  of 
the  mine  of  Tincroft,  in  Cornwall  : 

\Vhst  is  mount  by  TncttTix  ? 

Of  what  materials  is  the  matrix  of  ore  often  composed  ? 

What  difference  has  been  observed  in  the  veins  of  the  same  mine  which 
vary  in  direction  ? 

What  class  of  veins  in  Cornwall  appears  to  have  divided  and  heaved 
another  at  right  angles  to  it  ? 


CROSSING  OF  VEINS. 


191 


A,  B,  represents  the  surface  of  the  mine  with  a  vein  running 
from  north  to  south,  and  crossed  by  tin  and  copper  veins,  from  east 
to  west.  The  veins,  C,  D,  E,  are  veins  of  copper,  F,  G,  H,  veins 
of  tin,  and  I,  a  vein  yielding  both  tin  and  copper.  Two  of  the  cop- 
per, and  one  of  the  tin  veins,  running  east  and  west,  are  intersected 
by  the  non-metalliferous  north  and  south  veins,  by  which  they  are 
heaved  out  of  their  regular  course  towards  the  south.  It  may  also 
be  perceived  that  one  of  the  tin  veins,  F,  is  intersected  by  two  of, 
the  copper  veins,  C  and  D,  which  pass  through  it  without  affect- 
ing its  direction. 

17.  The  manner  in  which  copper  veins  intersect  those  of  tin, 
always  passing  through  them,  and  generally  heaving  them  from 
their  course,  may  be  understood  from  the  following  section  of  the 
Pink  mine : 


N 


A,  B,  may  be  supposed  to  represent  the  surface,  along  which 
runs  a  vein  from  north  to  south,  intersecting  metalliferious  veins, 
passing  from  east  to  west.  The  veins  C,  D,  E,  are  copper  veins, 

Construct  and  explain  the  plan  of  Tincroft  mine  ? 

Exhibit  and  explain  the  manner  of  heaving  out  a  tin  vein  by  one  of  copper. 


192  METALLURGY. 

and  F,  a  vein  of  tin  ;  and  here  it  will  be  seen  how  three  of  these 
veins  have  their  western  sides  heaved  towards  the  north,  by  the 
non-metalliferous  vein  passing  through  them.  The  tin  vein  run- 
ning near  the  southern  extremity  of  the  mine,  underlies  greatly 
towards  the  north,  while  the  copper  veins,  on  the  contrary,  under- 
lie towards  the  south.  One  of  the  latter  veins,  C,  meeting  the 
tin  vein,  F,  in  its  course,  interrupted  it,  and  heaved  that  part  of  it 
northward  of  the  point  of  intersection  twenty-four  fathoms  nearer 
to  the  surface,  and  the  same  tin  vein  was  interrupted  by  another 
copper  vein,  D,  and  heaved  about  ten  fathoms  towards  the  sur- 
face; a  third  time  it  was  cut  through  by  another  copper  vein,  E, 
not  shown  on  the  surface,  and  again  heaved  somewhat  out  of  its 
course. 

18.  Sometimes  one  vein  crosses  another  without  causing  any 
change  of  direction,  and  if  both  have  nearly  the  same  inclination, 
they  are  usually  richer  near  their  junction.     Where  two  veins  in 
the  same  district  have  the  same  direction,  or  run  parallel,  it  has 
been  observed  that  their  contents  are  similar;  but  where  they  run 
in  contrary  directions,  their  contents  are  dissimilar. 

19.  Molina,  in  his  History  of  Chili,  gives  an  account  of  a  vein 
of  silver  at  Uspalta,  in  the  Andes,  which  is  nine  feet  in  thickness 
throughout  its  extent,  having  been  traced  ninety  miles  ;  and  it  has 
smaller  veins  branching  off  on  either  side,  and  penetrating  the 
adjacent  mountains  to  the  distance  of  thirty  miles.     It  has  been 
conjectured  that  this  vein  reaches  300  miles. 

20.  In  Northumberland  and  Durham,  cross  courses  have  been 
found  to  contain  ore  near  their  junction  with   strong  veins.     In 
Cornwall,  at  Botallac  mine,  near  the  Land's  End,  a  cross  course  run- 
ning north  and  south,  is  enriched  by  the  junction  of  east  veins, 
which  have  been  compared  to  small  rivulets  opening  into  a  river. 
The  cross  course  is  rich  in  ore  to  the  extent  of  twenty  or  thirty 
fathoms  on  either  side  of  its  junction  with  a  vein,  but  no  veins  are 

found  branching  from  the  west  side  of  the 
cross  course.  The  vein  contains  gray 
copper  ore  of  a  fine  quality.  Sometimes 
a  vein  contains  tin  ore  in  the  centre,  sur- 
rounded laterally  by  copper  ore,  as  repre- 
sented in  the  marginal  figure. 

In  this  vertical  section  of  a  part  of  the 
vein,  T  denotes  the  central  portion,  con- 
sisting of  tin,  and  C,  C,  the  copper  ore 
on  each  side  of  it.* 

What  remark  has  been  made  respecting  the  junction  of  two  veins  which 
do  not  displace  one  another  in  crossing  ? 

What  description  has  been  given  of  a  vein  of  silver  ore  in  South  America? 

What  example  is  found  among  the  Cornish  mines  of  cross  courses  enrich- 
ing the  main  vein  ? 

In  what  arrangement  are  the  ores  of  tin  and  copper  sometimes  placed 
within  a  common  vein  ?  

*  Bakewell's  Introd.  to  Geology,  Silliman's  ed.  p.  300. 


GOLD — PLATINA SILVER.  193 

21.  The  different  metals  are  found  respectively  in  different  parts 
of  the  world,  in  various  situations,  and  associated  with  peculiar 
kinds  of  rocks,  stones,  sand,  or  alluvial  soil. 

Gold  is  found  in  America,  in  Mexico,  Brazil,  New  Granada,  Chili. 
Peru,  and  Buenos  Ayres  ;  in  the  United  States  it  is  found  in  Alaba- 
ma, Georgia,  North  and  South  Carolina,  Virginia,  and  probably  in 
some  of  the  states  farther  north  ;  in  Africa,  in  Kordofan,  Bambouk, 
and  on  the  eastern  coast  opposite  the  island  of  Madagascar,  and 
especially  in  Sofala,  supposed  to  be  the  country  of  Ophir,  mentioned 
by  the  Jewish  writers  ;  in  Asia,  in  Thibet,  Japan,  Formosa,  Cey- 
lon, Java,  Sumatra,  Borneo,  the  Philippines,  and  other  islands  of 
the  Indian  Archipelago,  in  Siberia,  in  the  Ural  and  Altai  mountains, 
between  the  rivers  Obi  and  Irtisch  ;  in  Europe,  in  Hungary,  Tran- 
sylvania, the  country  round  Salzburg,  and  the  Hartz  mountains, 
in  Piedmont,  in  Spain,  chiefly  in  the  Asturias,  and  the  Pyrenees, 
in  France,  in  rivers  occasionally  in  small  quantities,  and  formerly 
in  Thrace,  Macedonia,  and  some  of  the  Greek  islands. 

22.  Gold  occurs  in  primary  and  transition  rocks,  in  porphyry 
and  syenite,  and  in  the  lowest  sandstone  ;  it  has  been  occasionally 
found  in  coal,  and  sometimes  in  volcanic  rocks,  and  most  abun- 
dantly in  the  sands  of  rivers,  or  in  that  mixture  of  alluvial  matter 
called  cascalhao,  consisting  of  pebbles,  gravel,  and  minute  parti- 
cles of  siliceous  and  argillaceous  earths,  and  oxide  of  iron.     It  is 
usually  in  the  state  of  grains,  minute  scales,  or  pellets  of  various 
sizes,  and  it  is  thus  collected  by  the  African  negroes,  and  brought 
for  sale  in  ostrich  and  vulture  quills.     Sometimes  it  is  met  with 
in  large  masses ;  in  1730,  a  block  was  discovered  in  Peru,  weighing 
forty-five  pounds;  and  about  1810,  gold  was  obtained  from  several 
rivers  in  North  Carolina,  one  mass  weighing  twenty-eight  pounds. 
This  metal  is  sometimes  disseminated  in  threads  or  in  lamina?, 
alloyed  with  tellurium  and  silver,  and  it  is  likewise  mixed  with 
the  sulphurets  of  iron,  of  silver,  of  copper,  of  arsenic,  of  mercury, 
and  other  metals. 

23.  Platina  was  first  discovered  in  the  provinces  of  Choco  and 
Bogota  in  South  America,  and  it  has  since  been  found  in  the  pro- 
vince of  "Barbacoas,  near  the  shores  of  the  South  Sea;  in  Brazil, 
in  the  island  of  St.  Domingo,  in  North  America,  in  very  minute 
quantities  in  ores  of  argentiferous  grey  copper  at  Guadalcanal  and 
Casalla,  in  Spain ;  and  recently  in  greater  abundance  on  the  west- 
ern or  European  side  of  the  Ural  mountains,  in  the  territories  of 
Russia.     It  occurs  generally  in  the  sands  of  rivers,  intermixed 
with^ palladium,  rhodium,  osmium,  iridium,  and  other  metals. 

24.  Silver  is  found  in  America,  in  Mexico,  Peru,  Chili,  and 

In  what  countries  of  the  world  is  gold  found  ? 

In  what  species  of  rocks  is  it  discovered  ? 

Where  is  it  found  in  the  greatest  abundance  ? 

What  remarkable  masses  of  native  gold  have  been  met  with  ? 

Where  is  platina  found  in  the  greatest  abundance  in  the  present  day  ? 

In  what  situations  does  it  occur  ? 

With  what  other  metals  is  it  intermixed  ? 

E 


194  METALLURGY. 

Buenos  Ayres  ;  in  Asia,  in  China,  Thibet,  and  Siberia ;  in  Europe, 
in  Norway,  Sweden,  Hungary,  Saxony,  Transylvania,  Moravia, 
Austria,  Bohemia,  the  Tyrol,  Hanover,  Brunswick,  Prussia,  the 
Netherlands,  France,  Savoy,  and  Great  Britain;  but  in  the  latter 
only  as  a  subordinate  product  of  lead  or  copper  ores.  It  occurs 
principally  in  veins  in  primitive  rocks,  and  in  some  transition  and 
secondary  rocks. 

25.  Lead  is  found  in  America,  in  Mexico,  Brazil,  and  the  United 
States ;  in  the  Russian  empire  in  the  environs  of  Nertschinsk  on 
the  frontiers  of  Chinese  Tartary,  and  in  Armenia;  in  Europe,  in 
France,  Savoy,  the  Netherlands,  the  Prussian  States,  the  Hartz 
Mountains,   in   Saxony;  in  the   Austrian   dominions   and   other 
parts   of  Germany;   in  England,    especially  in  Derbyshire  and 
Lancashire;    in   Scotland,  In  Ireland,  and    in    Spain.     Galena, 
which  is  the  most  common  ore  of  lead,  occurs  in  primitive  as 
well  as  secondary  rocks,  and  in  Great  Britain  the  richest  mines 
are  in  slate  and  limestone.     Lead  ores  are  found  generally  in  the 
older  rocks,  except  trap  and  serpentine ;  in  porphyry  and  syenite, 
in  the  lowest  sandstone,  and  occasionally  in  strata  of  coal. 

26.  Copper  is  found  in  Eurvpe,  in   France,  Germany,  Tran- 
sylvania, Silesia,  Sweden,  Norway,  Great  Britain,  Ireland,  and 
Spain  ;   in  Asia,  in    Siberia,   Kamtschatka,  Japan,  China,  Per- 
sia, Arabia,  and  the  Indian  Islands ;  in  Africa,  in  Barbary,  Mo- 
rocco, Abyssinia,  in  the  mountains  north  of  the  Cape  of  Good 
Hope,  and  in  the  Namaqua  country;  in  America,  jn  the  North- 
western Territory,  in  Pennsylvania,  and  various  other  parts  of  the 
United  States,  in  Mexico,  Chili,  and  Brazil,  in  which  last  coun- 
try a  mass  was  discovered  weighing  2(>66  Portuguese  pounds.    It 
occurs  in  primitive  and  transition  rocks,  porphyry,  syenite,  and 
sometimes  in  sandstone,  in  coal  strata,  and  alluvial  soil. 

27.  Tin  is  found  in  England  more  abundantly  than  in  most 
other  countries,  mines  or  tin-works  of  some  kind  having  existed 
in  Britain  before  it  was  known  to  the  Romans,  and  it  was  imported 
from  that  island  by  the  mariners  of  Phenicia  and  Carthage.    The 
other  parts  of  Europe  in  which  it  principally  occurs,  are  Saxony, 
Bohemia,  and  France  :  the  quantity  found  in  Spain  and  Portugal 
is  inconsiderable.     In  Asia  it  is  found  in  China,  Siarn,  Pegu,  in 
Sumatra,  Ceylon,  Banca,  and  other  islands ;  and  in  America,  in 
Mexico  and  Buenos  Ayres.     It  is  considered  as  one  of  the  most 
ancient  of  rnetals,  having  been  discovered  only  in  primitive  rocks, 
as  granite,  gneiss,  mica-slate,  and  clay-slate,  or  disseminated  in 
soils  formed  from  the  decomposition  of  such  rocks. 

28.  Mercury  is  found  in  Europe,  in  France,  Bavaria,  the  Aus- 
trian dominions,  and  Spain,  and  in  Italy  arid  Sicily,  but  in  com- 
paratively small  quantities ;  in  Asia  the  most  productive  mines 

In  what  countries  "has  silver  been  found  ? 

In  what  class  of  rocks  are  lead  ores  most  abundant  ? 

What  countries  possess  mines  of  copper? 

In  what  variety  of  rocks  or  soils  does  it  occur  ? 

Why  is  tin  regarded  as  among  the  oldest  metals? 


NICKEL.  195 

are  in  China  and  Japan ;  and  in  America.,  in  Mexico  and  Peru, 
especially  that  of  Guancavelica.  Mercury  differs  from  the  metal 
just  noticed,  occurring  but  rarely  and  in  small  quantities  in  primi- 
tive countries,  the  principal  deposits  being  found  in  bituminous 
slate,  shell-limestone,  and  breccias.  Dolomieu  discovered  it 
among  the  products  of  volcanoes,  doubtless  sublimed  by  subter- 
ranean fires. 

29.  Iron  is  the  most  abundant  of  metals  in  every  part  of  the 
world,  and  is  found  in  Europe,  in  England,  Scotland,  in  Ireland 
more  rarely,  in  France,  Sweden,  Norway,  the  Austrian  empire, 
in  the  southern  part  of  Russia,  in  Bavaria,  Prussia,    Saxony, 
Hesse,  the  Netherlands,  Switzerland,  Savoy,  Piedmont,  Naples,* 
Sardinia,  Elba,  Spain,  and  Portugal;  in  Jlsia,  in  Siberia,  Arme- 
nia, Natolia,  Persia,  Arabia,  Tartary,  Indostan  and   China;  in 
Africa,  in  Morocco,  and  in  Congo  ;  and  in  America,  abundantly  in 
several  of  the  United  States,  in  Mexico,  and  Brazil.    This  metal 
is  so  generally  diffused  throughout  the  mineral  kingdom,  that,  as 
Mr.  Brande  observes,  "  there  are  comparatively  few  fossils  which 
can  be  said  to  be  perfectly  free  from  it."     There  is  no  kind  of 
rock  or  formation — primitive,  transition,  secondary,  alluvial,  or 
volcanic — in  which  it  does  not  make  its  appearance  ;  and  its  saline 
combinations,  being  dissolved  in  subterraneous  waters,  form  chaly- 
beate springs. 

30.  The  principal  mines  of  Antimony,  in  Europe,  are  those  ot 
Scotland,  Hungary,  Bohemia,  Saxony,  France,  Spain,  Transylva- 
nia, and  at  Neuweid,  below  Coblentz,  on  the  right  bank  of  the 
Rhine;  and  in  America,  in  Mexico  and  Brazil.    It  occurs  in  primi- 
tive and  transition  rocks,  exclusive  of  trapp  and  serpentine ;  and 
likewise  in  porphyry  and  syenite. 

31.  Bismuth  is  obtained  in  England,  France,  Germany,  and 
Sweden  ;  in  Siberia  and  in  Brazil ;  chiefly  from  mines  of  other 
metals.     It  appears  to  belong  exclusively  to  primitive  countries. 

32.  Zinc  is  found  in  Belgium,  in  the  territory  of  Limburg,  in 
Prussia,  Austria,  France,  Spain,  and  England  ;  in  Siberia,  where 
the  mines  are  not  worked  ;  and  in  America.     It  occurs  in  primi- 
tive, transition,  and  secondary  rocks,  calcareous,  argillaceous,  and 
siliceous. 

33.  Cobalt  is  found  in  Saxony,  Austria,  Prussia,  Hesse,  and 
other  parts    of  Germany,    Norway,  and    Sweden ;    likewise   in 
France  and  Spain,  but  the  mines  are  not  worked.     It  occurs  in 
primitive  mountains,  except  those  of  limestone,  trapp,  and  serpen- 
tine; and  likewise  in  transition  mountains,  and  in  sandstone. 

In  what  countries  is  mercury  found  in  the  greatest  abundance  ? 

In  what  classes  of  rocks  is  it  met  with  ? 

Which  of  the  metals  is  found  in  the  greatest  abundance  in  nature? 

What  has  been  remarked  of  its  prevalence  in  various  geological  forma- 
tions ?  In  what  countries  and  in  what  class  of  rocks  does  antimony  oc- 
cur ? — bismuth  ? — zinc  ? — cobalt  ? 

*  Oxidulated  iron  is  said  to  have  been  collected  on  the  sea-shore,  near 
Puzzuoli. 


196  METALLURGY. 

34.  Nickel  is  found  in  France,  Spain,  Bohemia,  and  in  England 
more  rarely;  likewise  in  Siberia;  and  it  is  a  general,  if  not  a 
constant  component  part  of  aerolites.     This  metal,  which  is  one 
of  the  least  abundant,  is  usually  met  with  in  the  same  situations 
with  cobalt  and  arsenic,  accompanying  the  ores  of  those  metallic 
bodies. 

35.  Manganese  is  among  the  products  of  the  mines  of  England, 
Scotland,  France,  Hungary,  Transylvania,  Saxony,  and  Bohemia. 
It  is  found  in  primitive  and  transition  mountains,  and  sometimes 
in  the  lower  stratified  rocks. 

36.  Chrome  occurs  in  France,  Norway,  the  Tyrol,  and  at  Eka- 
therineberg,  in  the  Ural  Mountains.     It  is  generally  embedded  in 
gneiss  or  mica-slate. 

37.  Arsenic  is  found  in  Saxony,  Silesia,  Baden,  Hungary,  and 
Transylvania;  and  in  England,  in  Cornwall;  in  Siberia,  in  Ar- 
menia, on  the  right  bank  of  the  Euphrates,  and  elsewhere ;  in 
the  tin-mine  of  Kianfu,  in  China ;  and  in  Mexico.     It  occurs  in 
primitive  and  transition  mountains  and  in  porphyry.* 

The  other  metals  have  scarcely  yet  been  applied  to  any  pur- 
poses of  utility;  and  most  of  them  are  of  rare  occurrence. 

JLrt  of  Mining. 

38.  The  working  of   mines   for   the  purpose   of  extracting 
metallic  ores,  may  be  supposed,  like  several  other  useful  arts, 
to  have  originated  from  accidental  circumstances.     It  has  been 
already  stated,  that  some  metals,  and  especially  gold  and  silver, 
have  been  occasionally  found  on  the  surface  of  the  earth,  or  at  an 
inconsiderable  depth  beneath  it ;  and  hence  it  may  not  unreasonably 
be  presumed,  mankind  first  became  acquainted  with  the  treasures 
of  the  mineral  kingdom  of  nature.     But  though  accident  might 
have  led  to  the  discovery  of  the  precious  metals,  which  always 
occur  in  a  state  of  purity,  or  else  mechanically  mixed  with  other 
substances,  that  is  by  no  means  the  case  with  the  metals  in  gene- 
ral, by  far  the  greater  number  being  obtained  in  the  form  of  ores, 
consisting  of  sulphurets,  oxides,  chlorides,  or  metallic  salts,  con- 
stituting chemical  compounds,  often  presenting  to  the  inexpe- 
rienced eye  no  traces  whatever  of  the  usual  characteristics  of  a 
metallic  body. 

39.  If  metals  in  such  a  state,  had  been  commonly  dispersed 

In  what  countries  and  in  what  class  of  rocks  does  nickel  occur? 
With  what  metals  is  nickel  commonly  associated  ? 
In  what  countries  and  in  what  situations  is  manganese  found  ? 
Where  is  chrome  obtained  ? — arsenic  ? 

How  may  we  suppose  the  working  of  metals  to  have  originated  ? 
In  what  four  classes  of  compounds  does  the  greater  number  of  metals 
occur  in  nature  ? 

*  Nouv.  Diet.  d'Hist.  Natur.  appliquee  aux  Arts,  &c.  Paris,  torn.  xxi. 
1818;  Art.  MINE;  Bake  well's  Introd.  to  Geology,  chap.  xix. ;  and  Metal- 
lurgie  Pratique,  formant  paftie  de  la  Bibliotheque  Industrielle.  Paris,  1827 


DISCOVERY  OF  METALLIC  ORES.  197 

on  the  superfices  of  the  terrestrial  globe,  they  might  forages  have 
passed  unnoticed  or  unappropriated,  till  their  real  nature  and  com- 
position had  been  developed  by  some  fortunate  accident,  or  ascer- 
tained by  the  slow  process  of  observation  and  experiment.  Some 
have  ascribed  the  discovery  of  the  nature  of  metallic  ores,  and 
of  the  method  of  reducing  them,  to  the  conflagration  of  forests  on 
the  sides  of  metalliferous  mountains. 

40.  Bishop  Watson  says,  "  The  most  obvious  method  of  clear- 
ing a  country  of  its  wood  is  setting  it   on  fire;  now  in   most 
mineral  countries  there  are  veins  of  metallic  ores,  which  lie  con- 
tiguous to  the  surface  of  the  earth,  and  these  having  been  fused 
whilst  the  woods   growing  over  them  were   on  fire,   probably 
suggested  to  many  nations  the  first  idea  of  smelting  ores : 

'  Powerful  gold  first  raised  his  head, 

And  brass  and  silver,  and  ignoble  lead  : 
When  shady  woods  on  lofty  mountains  grown, 
Felt  scorching  fires  ;  whether  from  thunder  thrown, 
Or  else  by  man's  design  the  flames  arose — 
Whatever  'twas  that  gave  these  flames  their  birth, 
Which  burnt  the  tow'ring  trees  and  scorch'd  the  earth; 
Hot  streams  of  silver,  gold,  and  lead,  and  brass, 
As  nature  gave  a  hollow,  proper  place, 
Descended  down  and  formed  a  glitt'ring  mass.' 

41.  "There  is  no  natural  absurdity  in  this  notion  of  the  poet; 
and  indeed  it  is  confirmed  by  the  testimony  of  various  ancient 
historians,  who  speak  of  silver  and  other  metals  being  melted  out 
of  the  earth  during  the  burning  of  the  woods  upon  the  Alps  and 
the  Pyrenees.     A  similar  circumstance  is  said  to  have  happened 
in  Croatia,  in  the  year  1762 ;  a  large  mass  of  mixed  metal,  com- 
posed of  copper,  iron,  tin,  and  silver  having  been  fluxed  during 
the  conflagration  of  a  wood  which  was  accidentally  set  on  fire."* 

42.  The  discovery  of  the  existence  of  veins  of  metallic  ores  within 
the  bowels  of  the  earth,  whether  it  originated  solely  from  the  re- 
searches undertaken  in  consequence  of  such  fortuitous  circum- 
stances as  those  here  specified,  or  from  some  other  causes,  must 
have  led  to  some  of  the  simpler  processes  of  mining ;  and  the  art 
must  have  been  improved  and  extended,  like  other  arts,  by  the 
invention   of  methods  for  overcoming  occasional  obstacles,  and 
through  the  necessity  that  from  time  to  time  occurred  of  making 
experimental  researches. 

43.  In  the  prosecution  of  such  undertakings  the  miner  must 
frequently  be  guided  by  appearances,  on  which  he  may  perhaps 
be  induced  to  rely,  without  being  at  all  able  to  trace  their  con- 
nexion with  the  objects  of  which  he  is  in  quest.    "  Thus  a  green, 

To  what  occurrences  has  the  discovery  of  the  art  of  working  metals 
been  ascribed  ? 

What  testimony  have  we  of  the  correctness  of  this  supposition? 

*  Chemical  Essays,  vol.  v. 

R2 


1 98  METALLURGY. 

earthy  matter  is  a  good  symptom  in  a  tin  mine ;  a  brown,  ochry 
earth,  and  compact  iron  pyrites,  are  regarded  as  favourable  omens 
in  a  copper  mine.  Detatched  pebbles  of  ore,  or  fragments  of 
veinstones,  have  sometimes  led  to  the  riches  of  the  vein ;  and  tin 
has  especially  been  thus  discovered  in  Cornwall.  The  miners, 
though  a  shrewd  class  of  people,  are  often  preyed  upon  by  the 
most  vulgar  superstition,  and  many  ancient  absurdities  are  still 
retained  and  cherished  in  their  art.  The  divining-rod  and  other 
oracles  are  yet  consulted  ;  genii  are  said  to  preside  over  the  mines, 
and  he  who  inadvertently  whistles  when  below  ground,  breaks 
the  spirits  of  his  companions  for  the  day,  though  freely  permitted 
to  indulge  in  his  musical  disposition  in  the  form  of  a  song. 

44.  "  In  older  mineralogical  works,  we  read  much  upon  these 
and  other  subjects.     Flames  of  light   have   been   described    as 
playing  over  a  district  which  afterwards  has  been  found  to  contain 
subterranean   riches  ;  and  this  may  have  arisen  from   the   good 
electrical  conducting  powers  of  the  vein.     The   waters   issuing 
from  the  soil  sometimes  hold  metallic  salts  in  solution,  and  re- 
positories of  metals  have  been  discovered  by  circumstances  of 
this  kind.     Copper  veins  tinge  waters  blue,  and  a  piece  of  grease 
put  into  them  becomes  rapidly  stained  of  that  colour.    There  is  no 
popular  notion  more  common  than  that  metals  grow  in  the  veins ; 
an  idea  which  may  very  probably  have  originated  from  observing 
the  depositions  of  one  metal  by  the  introduction  of  another  into 
its  solution,  as  when  silver  is  precipitated  by  the  introduction  of 
a  plate  of  copper  into  its  solution,  or  copper  by  iron. 

45.  Districts  rich  in  metals  are  generally  barren,  and  seem  pe- 
culiarly dreary  and  desolate  to  the  traveller.     This  partly  arises 
from  the  nature  of  the  strata,  and  partly  from  the  heaps  of  rubbish 
and  hills  of  stone  thrown  upon  the  surface,  and  partly  from  the 
operations  carrying  on  in  the  vicinity  being  inimical  to  vegetation. 
The  high  road  through  Cornwall,  especially  near  Redruth,  is  an 
excellent  specimen  of  this  kind  of  country ;  while,  at  the  same 
time  the  romantic  beauty  and  luxuriant  vegetation  of  many  parts 
of  that  county  and  of  Devonshire,  prove  that  exterior  cultivation 
is  not  always  incompatible  with  internal  riches.     The  neighbour- 
hood of  the  Parys  mountain,  in  Anglesea,  is  singularly  marked  by 
sterility  and  gloominess.     The  soil,  naturally  unproductive,  is 
rendered  more  so  by  the  poisonous  waters  that  traverse  it,  and  by 
Ihe  sulphurous  vapours  that  float  around.     There  are  not  only  no 

What  exterior  characters  of  the  ground  are  often  relied  on,  to  indicate 
the  presence  of  metallic  ores  beneath  the  surface? 

What  superstitions  are  prevalent  in  mining  districts  ? 

What  aid  have  the  waters  of  a  country  been  found  to  afford  in  judging 
of  its  mineral  treasures  ? 

What  notion  is  entertained  respecting  the  growth  of  metallic  veins  ? 

What  state  of  soils  appears  to  prevail  in  mining  districts  ? 

To  what  is  this  attributed  ? 

By  what  circumstance  incident  to  mining  operations  is  the  natural  ste- 
rility of  the  soil  increased  ? 


MINING  PROCESSES. 


199 


shrubs  and  trees,  but  the  barrenness  is  unrelieved  even  by  a  single 
blade  of  grass,  or  the  rusty  green  of  a  hardy  lichen."* 

46.  The  construction  of  works  in  mines  must  vary  according  tc 
circumstances,  as  the  forms  of  hills,  the  position  of  ores  in  beds 
or  viens,  and  the  obstacles  to  be  encountered  in  excavating  them. 
Sometimes  mines  are  formed  by  driving  a  level  from  the  mountain 
to  reach  the  vein,  the  contents  of  which  may  be  removed  through 
this  lateral  opening,  in  which  case  shafts  are  only  required  for  ven- 
tilation.   This  seems  to  be  among  the  simplest  modes  of  opera- 
tion ;    and  another  is,  following  the  ore  from  its  outlet  at  the  sur- 
face as  far  as  circumstances  will  allow.     When  regular  metallic 
viens  are  found  in  primitive  rocks,  they  are  sometimes  worked  to 
great  depths  by  more  varied  and  extensive  operations,  being  oc- 
casionally carried  below  the  level  of  the  sea.     In  such  cases  per- 
pendicular shafts  are  formed,  by  means  of  which  the  accumulating 
water  is  drained  by  machinery ;  and  these  shafts  communicate 
with  levels  driven  upon  the  lode  or  vein  at  various  depths. 

47.  The  art  of  mining  comprises  a  variety  of  processes,  essen- 
tial or  accessory,  the  most  important  of  which  are  included  in  the 
following  enumeration: — (1.)  Works  of  research,  undertaken  for 
the  purpose  of  discovering  metallic  beds  or  viens.     (2.)  The  con- 
struction of  shafts  and  galleries.    (3.)  The  tracing  of  the  bearing, 
direction,  and  probable  extent  of  the  mineral  deposits.    (4.)  Exca- 
vating the  metallic  ores.     (5.)  Works  requisite  for  ensuring  the 
security  of  the  shafts  and  galleries  ;  as  propping,  planking,  plaster- 
ing, walling,  building  arches,  &c.    (6.)  Making  air-shafts  or  fun- 
nels, and  other  arrangements  necessary  for  securing  a  proper  venti- 
lation, throughout  the  works.  (7.)  Methods  of  raising  or  transport- 
ing ores  or  minerals  to  the  surface.    In  the  mines  of  England  and 
Silesia,  iron  railroads  or  canals  are  sometimes  constructed  Tor  the 
conveyance  of  the  mineral  produce  ;  as  in  the  Worsley  coal-mines, 
in  Lancashire,  where  subterranean  canals  were  formed  by  the  cele- 
brated Brindley,  before  the  middle  of  the  last  century. 

48.  In  the  iron  mines  at  Fahlun,  in  Sweden,  and  in  the  mines  of 
rock-salt,  in  Galitzia  and  elsewhere,  when  the  excavations  are  suf- 
ficiently capacious,  horses  are  sometimes  introduced  to  work  under 
ground,  a  practice  which  does  not  appear  to  have  been  adopted  in 
England  ;  though  those  animals  were  commonly  employed  to  work 
machinery  on  the  surface,  before  the  introduction  of  steam-engines 
into  the  mining  districts,  and  are  still  used  in  many  situations. 

What  is  one  of  the  simplest  modes  of  arriving  at  subterranean  veins  of 
ore  ?  In  what  manner  is  this  effected  in  level  countries  ? 

What  is  meant  by  the  term  lode  in  mining  ? 

What  is  the  first  kind  of  labour  connected  with  this  art  ? 

What  is  the  second  ?  third  ?  fourth  ? 

What  kind  of  precautionary  operations  do  the  preceding  labours  require  ? 

What  works  are  necessary  with  a  view  to  the  health  and  comfort  of  the 
miners  ? 

What  for  the  removal  of  the  products  of  the  mine  ? 

*  Brande's  Lectures  on  Geology,  lect  vi. 


200  METALLURGY. 

(8.)"Removing  or  stopping  out  water.  (9.)  The  accessory  opera- 
tions of  blasting  rocks  with  gunpowder,  or  firing  them  by  kindling 
on  their  surface  large  piles  of  wood,  and  thus  causing  them  to  split 
by  the  effect  of  heat,  as  is  practised  in  the  mines  of  Rammelsberg, 
in  the  Hartz  ;  those  of  Geyer  and  Altenberg,  in  Saxony  ;  of  Fel- 
sobanya,  in  Transylvania ;  of  Kongsberg,  in  Norway  ;  and  others. 
(10.)  Among  the  most  important  accessory  arrangements  are  those 
which  relate  to  lighting  the  mines  and  providing  against  the  dan- 
ger of  explosion  where  the  inflammable  vapour  called  fire-damp 
occurs ;  and  to  obviate  this,  various  plans  have  been  adopted,  as 
the  use  of  steel-mills,  and  Davy's  wire  gauze  lamps.* 

49.  Any  detailed  notice  of  mining  operations,  though  it  might  be 
rendered  interesting,  would  be  quite  inconsistent  with  the  plan  of 
this  work ;  but  a  few  particulars  may  be  added,  relative  to  the 
manner  in  which  gold  and  silver  mines  were  worked,  both  in 
Europe  and  America,  in  the  seventeenth  century;  and  also  con- 
cerning the  modes  of  proceeding  at  present  among  the  miners  in 
Cornwall,  England. 

50.  At  Kremnitz,  in    Hungary,  there  is  a  gold  mine,  which 
when  it  was  visited  by  Dr.  Browne,  about  1680,  had  been  worked 
nine  hundred  and  fifty  years.    It  was  nine  or  ten  English  miles  in 
length,  having  one  horizontal  passage  or  gallery,  eight  hundred 
fathoms  in  length,  called  the  Erbstall.  Its  depth  was  above  one  hun- 
dred and  seventy  fathoms.   "Ladders  were  not  used  to  descend 
into  the  mine,  but  persons  were  let  down  by  a  cable,  to  which 
was  affixed  a  seat  of  leather,  affording  a  safe  and  convenient  car- 
riage even  to  those  who  were  not  used  to  it.     There  were  six 
shafts  or  perpendicular  pits  that  might  be  entered  in  this  manner, 
each  having  a  distinct  name  :  (1.)  That  of  Rodolphus.  (2.)  Queen 
Anne.^3.)  Ferdinand.  (4.)  Matthias.  (5.)  Windshaft.  (6.)  Leopold. 

51.  "I  went  down,"  says  the  traveller,  "by  the  pit  of  the  em- 
peror  Rodolphus,  gently  descending  by  the  turning  about  of  a 
large  wheel,  to  which  the  cable  is  fastened,  one  hundred  and  eight 
fathoms  deep  into  the  earth ;  and  after  many  hours  being  in  the 
mine,  was  drawn  out  again  by  Leopold's  pit,  straight  up,  above 
one  hundred  and  fifty  fathoms,  a  height  surpassing  that  of  the 
pyramids  by  a  third  part.     At  the  bottom  of  which  pit  I  was  not 
discouraged  to  find  myself  so  deep  in  the  earth,  for  considering 
I  was  yet  above  three  thousand  miles  from  the  centre, f  I  thought 
myself  but  in  a  well.  It  is  built  on  all  sides  with  fir-trees,  one  lying 
upon  another,  (like  tranverse  logs,)  on  the  four  sides,  from  the 
top  to  the  bottom.     The  miners  work  towards  one,  two,  or  three 
of  the  clock,  as  they  speak;  for  they  direct  themselves  under 
ground  by  a  compass,  not  of  thirty-two  points  (such  as  is  used 

In  what  two  ways  is  heat  applied  to  split  the  rocks  of  mines? 

How  is  light  obtained  in  underground  operations  ? 

What  account  is  given  by  Dr.  Browne  of  the  Hungarian  gold  mines? 

*  See  Scientific  Class  Book,  pt.  i.  p.  326  5  also,  Treatise  on  Chem.  No.  282. 
t  Nearer  four  thousand  miles.     See  Scientific  Class  Book,  pt.  i.  p.  451. 


SILVER  MINES  OF  POTOSI.  201 

at  sea,)  but  by  one  of  twenty-four,  which  they  divide  as  we  do  the 
hours  of  the  day,  into  twice  twelve."* 

52.  The  silver  mines  of  Potosi,  in  Peru,  which  are  among  the 
richest  hitherto  known,  were  discovered  in  1545.     For  the  more 
convenient  working  of  the  mines,  the  Spaniards  dug  galleries, 
which  they  call  socabonos,    from  the  foot  of  the  mountain  of 
Potosi,  towards  the  west,  passing  through  horizontally  to  the  mine, 
each  gallery  being  eight  feet  broad  and  a  fathom  deep,  and  closed 
with  gates  that  might  be  locked,  through  which  the  silver  is 
carried  out,  and  where  the  owner  of  the  socabon  receives  a  fifth 
part.     The  socabon  leading  to  the  rich  vein  was  begun  in  1556, 
and  finished  in  twenty-nine  years,  extending  two  hundred  and 
fifty  rods  in  length.     The   miners  work  by  candlelight,  both  day 
and  night,  by  turns :  those  that  work  in  the  day  sleeping  in  the 
night,  and  those  that  work  in  the  night  sleeping  in  the  day. 

53.  The  ore,  which  is  as  hard  as  a  stone,  is  cut  out  with  pick- 
axes, beaten  in  pieces  with  an  iron  crow,  and  carried  by  the  miners, 
upon  their  backs,  up  ladders  made  of  leather.     Each  ladder  has 
three  leathern  ropes,  about  the  thickness  of  a  cable,  stretched  out 
by  %ticks,  so  that  one  labourer  may  go  up  on  one  side,  while 
another  comes  down  on  the  other.    Each  ladder  being  ten  fathoms 
in  length,  has  its  respective  floor,  on  which  the  labourers  rest 
during  their  ascent;  the  number  of  the  floors  differing  according 
to  the  depth  of  the  mine.     The  men  carry  the  ore  in  bags  fastened 
before  their  breasts,  and  passing  over  their  shoulders  behind  their 
backs ;  going  up  three  and  three  together,  the  foremost  with  a 
lighted  candle  tied  to  his  thumb,  so  that  both  hands  are  at  liberty. 
Thus  loaded  they  scramble  up  and  down  one  hundred  and  fifty  fa- 
thoms; exposed,  besides  other  perils,  to  the  danger  of  destruction 
from  the  falling  in  of  the  mines,  or  of  part  of  the  sides  of  the  ill-con- 
structed pits  or  shafts.     They  suffer  also  from  the  cold  temperature 
of  these  subterranean  passages.   The  silver  runs  for  the  most  part 
between  two  rocks,  as  in  a  long  channel ;  one  side  being  as  hard 
as  flint  aud  the  other  much  softer. f 

54.  This  defective  and  laborious  method  of  working  the  mines 
in  South  America,  seems  to  have  been  retained  till  the  foundation, 
of  independent  states  in  that  part  of  the  new  world,  on  the  ruins 
of  the  long  misgoverned  Spanish  colonies.    The  improvements 
which  have  taken  place,  however,  have  been  chiefly,  if  not  entirely, 
owing  to  the  investment  of  British  property  in  the  mines  of  Peru.- 

VVhat  is  meant  by  working  towards  "  one  two  or  three  o'clock,  &c.  ? 

How  early  were  the  Peruvian  silver  mines  discovered  ? 

In  what  manner  are  these  mines  approached  ? 

What  is  the  consistency  of  the  ore  of  Potosi  ? 

In  what  manner  is  it  removed  ? 

How  long  was  the  old  South  American  system  of  mining  retained  ? 

*  Sir  Thomas  Pope  Blount's  Natural  History,  pp.  229 — 231 ;  from  Tra- 
vel's in  Hungaria,  &c.,  by  Edw.  Browne,  M.  D. 
t  Sir  T.  P.  Blount's  Natural  History,  pp.  242—244, 


202  METALLURGY. 

Fifteen  or  sixteen  years  since  steam-engines  were  sent  from  En- 
gland, which  were  used  in  working  the  shallow  mines  of  Pasco; 
and  as  Mr.  Phillips  observed,  "It  may  be  assumed  that  the  supe- 
rior skill  of  the  British  miners,  assisted  by  the  power  of  the  steam- 
engine,  where  wood  or  coal  is  found  in  sufficient  abundance  for 
fuel,  will  be  able  to  accomplish  much  more  than  could  be  performed 
by  systems  so  rude,  if  system  it  could  be  called,  where  no  regu- 
larity existed  in  the  underground  workings."* 

55.  The  principal  mining  districts  in  South  Britain,  whence 
metals  are  procured,  are  in  Cumberland,  Lancashire,  Derbyshire, 
North  Wales,  and  Cornwall.  Those  parts  of  the  north  of  England, 
in  which  lead  is  chiefly  found,  are  more  mountainous  than  the 
metalliferous  tracts  in  Cornwall,  and  the  mines  in  general  are  in 
elevated  situations;  and  not  being  very  deep,  the  water  may  be 
readily  discharged  by  cutting  a  passage  or  adit,  through  which  it 
may  flow  into  the  valleys,  and  thence  to  the  sea.     Hence  steam- 
engines  are  but  little  needed,  and  a  very  great  expense  is  saved. 
But  in  the  mining  districts  of  Cornwall  steam-engines,  and  some 
of  enormous  power,  are  constantly  used ;  the  water-wheels  being 
comparatively  few.     The  mining  tracts  are  but  little  elevated, 
seldom  exceeding  500  feet  above  the  level  of  the  sea ;  and  the 
streams  of  water  are  but  inconsiderable  in  point  of  dimensions  or 
power. 

56.  In  Cornwall,  it  has  been  observed,  that  the  difficulty  is 
not  where  to  find  a  vein,  but  where  to  find  a  good  one.     A  good 
neighbourhood;  a  fine  gossan  (a loose,  friable,  ochreous  substance, 
principally  siliceous)  in  the  upper  part  of  the  vein  or  lode ;  plenty 
of  black  Jack,    (blende,)  for    "  black   Jack "    says   the   miner, 
"rides  a  proud  horse :"  and  if  at  some  depth,  on  cutting  the  lode, 
the  mine  is  inundated  with  water,  these  are  symptoms  of  encou- 
ragement for  the  miner,  even  if  little  or   no  copper  ore  should 
appear  near  the  surface.     Having  selected  the  vein  he  means  to 
work,  and  secured  the  right  of  working  it,  by  obtaining  a  lease  of 
the  mine  for  a  term  of  years,  it  is  necessary  to  determine  what 
part  of  the  vein  to  begin  upon,  which,  however,  is  often  decided 
by  convenience,  or  the  facility  of  bringing  up  to  it  an  adit  from 
the  lowest  ground  within  the  settled  limits.     The  next  object  is 
to  sink  a  shaft,  the  underlie  of  the  lode  being  first  determined, 
often  by  sinking  down  a  short  distance  from  the  surface  on  its 
course.    The  shaft,  however,  is  seldom  continued  in  this  direction, 
but  is  in  general  carried  down  vertically. 

To  what  may  we  look  for  improvements  on  that  system  in  ihe  future 
operations  in  the  mines  of  that  country  ? 

How  are  mines  in  the  North  of  England  freed  from  water  ? 

Why  may  not  the  same  plan  be  adopted  in  the  Cornish  mines  ? 

What  disadvantage  is  felt  by  mining  districts  near  the  level  of  the  sea  ? 

What  exterior  indications  encourage  the  miners  to  hope  for  rich  veins 
of  copper  ? 

*  Outlines  of  Mineralogy  and  Geology,  4th  edit.  p.  196. 


CORNISH  MINES.  203 

57.  Thus  if  a  copper  lode  or  vein  runs  east  and  west  through  a 
hill,  the  adit  is  driven  from  near  the  base  of  the  hill  to  the  lode 
underlying  north,  and  through  it  to  the  shaft,  which  is  perpen- 
dicular.    The  place  of  the  shaft  on  the  surface  is  to  be  determin- 
ed by  the  underlie  of  the  lode;  from  knowing  which  the  miner 
decides  on  sinking  his  shaft,  so  as  to  cut  or  traverse  the  lode  at  a 
particular  depth  beneath  the  surface,  according  to  circumstances. 
When  the  miner  wishes  to  examine  the  lode  above  the  level  of 
the  adit,  he  forms  a  cross-cut  or  passage  from  the  shaft  to  the 
lode,  and  in  the  same  manner  other  cross-cuts  may  be  made  be- 
low the  adit,  running  parallel  with  it,  and  extending  to  the  lode. 
In  either   case    he  may   be   incommoded  by  water,  and   conse- 
quently it  will   now  be  necessary  to  erect  machinery  near  the 
mouth  of  the  shaft,  for  the  purpose  of  raising  and  discharging  the 
water ;  and  it  will  also  serve  to  raise  the  ore,  as  well  as  any  rub- 
bish which  requires  removal  from  below. 

58.  Thus  the  miner  may  continue  to  explore  the  lode,  to  such 
a  depth  as  he  thinks  proper,  or  as  far  as  he  can  conveniently. 
Should  he  perceive  indications  of  a  rich  lode,  however,  instead  ol 
making  more  cross-cuts,  he  will  probably  be  induced  to  extend 
his  working  horizontally  in   the  lode  itself,   as  far  as  may  be. 
desirable  in  either  direction,  examining  it  thus  in  several  places, 
and  hollowing  out  as  he  proceeds  those  passages  in  the  mine 
which  he   terms   levels.     As   the   cross-cuts   are   generally  ten 
fathoms  apart,  he  describes  the  place  in  which  his  work  is  pro- 
ceeding, in  raising   ore,  for   instance,  by. saying  that  it  comes 
from  the  ten  or  twenty  fathom  level  going  east  or  west  from  such 
a  shaft,  each  shaft  having  its  own  designation ;  but  only  such 
levels  are  reckoned  as  are  below  the  adit. 

59.  In   sinking   the   shaft,   or   driving  the   cross-cut,  or   ex 
tending   on    the   lode,   the   miner   sometimes   finds   that   he    is 
in  want  of  air;  not  that  the  fire-damp  occurs,  as  in  some  coal- 
mines,  causing   so   many    fatal   accidents ;    but  that    the    vital 

Sart  of  it  is  so  nearly  consumed,  that  the  very  candle  burns 
imly  ;  and  this  would  be  a  sufficient  indication  to  the  miner,  even 
if  his  own  breathing  were  not  affected  by  it.  This  want  of  air, 
however,  is  rarely  felt  when  there  are  in  the  mine  several  shafts 
connected  by  underground  workings ;  and  when  it  does  happen,  a 
supply  of  atmospheric  air  is  obtained  by  means  of  a  pipe  or  trunk  of 
wood  or  metal,  extending  from  about  six  feet  above  of  the  surface 
to  the  lowest  part  of  the  workings,  or  to  such  a  place  as  may  be 
most  convenient,  and  having  on  the  top  a  wooden  box  turned  to 
the  wind ;  and  there  is  a  more  effectual  mode,  which  consists  in 
placing  on  the  top  of  a  pipe,  the  upper  part  of  which  is  of  iron,  a 
small  stove  or  grate,  containing  coal,  inclosed  in  such  a  manner 
that  the  fire  can  only  be  supported  by  drawing  its  supplies  of  air 

How  is  the  inclination  or  underlie  of  a  metallic  vein  determined? 
How  are  adits  dug  with  reference  to  the  underlie  of  the  lode? 
What  is  meant  by  "  levels"  in  the  working  of  a  mine  ? 
By  what  devices  is  the  want  of  fresh  air  supplied  ?     What,  besides  the 
difficulty  of  breathing,  apprizes  the  miner  that  the  air  is  becoming  impure  ? 


204  METALLURGY. 

from  the  bottom  of  the  working ;  and  thus  the  foul  air  passes  up 
the  pipe,  and  a  constant  current  is  kept  up ;  the  candle  then  re- 
sumes its  splendour,  which,  however,  is  but  feeble  at  the  best, 
and  the  miner  breathes  more  freely. 

60.  If  the  quantity  of  water  which  enters  the  mine  be  so  great 
that  it  cannot  be  discharged  fast  enough  by  a  horse-wheel  and 
buckets,  and  circumstances  do  not  admit  of  the  erection  of  ?.  water- 
wheel   sufficiently  powerful,  the  only  resort  is  a  steam-engine. 
Two  large  steam-engines  are  not  uncommonly  employed  in  one 
mine ;  and  there  are  many  instances  in  which  one  engine,  with 
its  apparatus  and  pumps,  together  with  the  expense  of  sinking  a 
large  shaft  on  which  to  place  it,  have  cost  more  than  forty-five 
thousand  dollars.     The  miner  does  not  calculate  the  power  of  his 
engine  with  reference  to  horse-power,  but  by  the  diameter  of  the 
cylinder.     The  cylinders  of  the  largest  engines  in  Cornwall  are 
91  inches  in  diameter.     There  are  two  of  90  inches  on  "  the  Con- 
solidated mines. 

61.  As  an  extreme  instance  of  the  prevalence  of  water  in  some 
mines,  it  may  be  mentioned,  that  from  one  in  the  western  part  of 
Cornwall,  not  many  years  ago,  after  a  long  series  of  very  wet 
weather,  the  engines  were  computed  to  draw  off  1600  gallons 
every  minute,  day  and  night,  during  six  weeks.  The  steam-engine 
or  engines  are  commonly  placed  on  the  largest  and   the  deepest 
shafts  in  the  mine.     An  ordinary  shaft,  or  one  which  is  only  to 
contain  the  ladder,  (for  the  miner  always  descends  by  the  ladder, 
never  by  the  rope,  as  in  coal-mines,)  is  only  just  large  enough  for 
that  single  purpose ;   but  the  engine  shaft,  as  it  is  termed,  is  ge- 
nerally large  enough  to  admit  of  two  divisions,  one  for  the  pumps, 
and  another  for  the  bucket  or  kibble,  and  sometimes  a  third  division 
as  a  footway  or  ladder ;  and  the  bottom  of  this  shaft  is  generally  the 
deepest  part  of  the  mine,  and  is  termed  by  the  miner  the  sump. 
In  the  bottom  of  it,  to  which  the  pumps  extend  from  the  summit, 
the  waters  of  the  mine  collect  by  means  of  the  underground  work- 
ings connected  with  it,  and  the  incessant  drainage  into  it  from 
the  country  or  rock,  in  which  the  mine  is  situated.     But  besides 
being  employed  in  discharging  the  water  of  a  mine,  the  steam- 
engine  is  sometimes  used  for  the  raising  of  ores,  which  it  does 
with  a  rapidity  far  greater  than  can  be  attained  by  any  other 
means ;  sometimes,  however,  very  small  engines,  termed  steam- 
whims,  are  erected  for  this  purpose  alone,  in  such  mines  as  are 
very  rich.* 

To  what  are  miners  compelled  to  resort  in  cases  where  great  quantities 
of  water  enter  the  mine  ? 

What  remarkable  instance  of  interference  from  water  in  mines  has  been 
experienced  ? 

In  what  situations  are  the  engines  for  discharging  water  commonly 
placed  ? 

What  is  meant  by  the  sump  of  a  mine  ? 

What  by  the  kibble  ? 

What  name  is  given  to  the  engines  which  raise  only  ore  from  a  mine  ? 

*  See  Philips's  Outlines,  p.  198,  &c. 


SECTION  OF  A  MINE. 


205 


62.  Dolcoath  mine,  situated  at  the  northern  foot  of  Carnbrae, 
a  granite  hill,  contiguous  to  Redruth  on  the  west,  is  one  of  the 
deepest,  if  not  the  deepest  in  Cornwall,  being  about  250  fathoms 
from  the  surface  to  the  sump.  This  mine  has  been  working 
above  fifty  years,  and  is  still  rich,  and  its  underground  workings 
are  very  extensive.  The  copper  mine  of  Ecton,  in  Staffordshire, 
is  now  worked  at  the  depth  of  472  yards,  being  the  deepest  in 
England.  The  deepest  mine  in  Europe,  or  in  the  world,  is  said 
to  be  that  of  Truttenberg,  in  Bohemia,  which  is  worked  1000 
yards  below  the  surface. 


63.  The  preceding  section  of  an  extensive  mine  will  serve  to 
give  the  reader  some  notion  of  the  forms  and  directions  of  the 

What  are  the  depths  of  some  of  the  deepest  mines  in  Europe  ? 
Draw  and  explain  the  section  of  a  mine. 

S 


206  METALLURGY. 

shafts,  galleries,  or  cross-cuts,  and  other  works  requisite  for  the 
extraction  of  the  ores  of  metals  from  the  bowels  of  the  earth. 

A.  Principal  shaft,  for  raising  water  and  ores  :  this  pit  commu- 
nicates above  with  a  horse-wheel,  and  lower  down  with  the  adit 
F,  and  inferior  galleries  or  cross-cuts. 

B.  Water-wheel  to  work  pumps  or  other  machinery  in  the  adit 
or  gallery  F. 

C.  Large  air-shaft,  communicating  with  the  lowest  gallery, 

D.  D.  Shafts  of  communication  between  the  galleries. 

E.  E,  E,  E.  Galleries  at  different  depths,  in  the  line  of  the 
vein  or  lode,  for  the  extraction  of  ores  or  water. 

F.  Principal  gallery,  or  adit,  for  the  discharge  of  water  raised 
into  it  by  pumps,  or  descending  from  works  in  the  higher  part  of 
the  mountain  in  which  the  mine  is  situated. 

G.  Horizontal  wheel,  (worked  by  horses,)  round  barrels  fixed 
to  the  axis  of  which  pass  ropes,  extending  over  pulleys,  and  de- 
scending into  the  shaft  A. 

H.  Large  shaft  traversing  the  lode,  extending  from  the  surface 
to  the  bottom  of  the  mine,  and  serving  for  the  descent  of  miners, 
and  as  an  air-shaft.  Stages  or  floors  are  placed  in  it  at  short  dis- 
tances, to  lessen  the  danger  of  accidents. 

(34.  Such  are  the  usual  arrangements  adopted  for  the  works  of 
mines,  in  most  situations,  and  under  favourable  circumstances. 
In  particular  cases,  however,  additional  constructions  are  required 
for  the  prosecution  of  such  undertakings.  The  galleries  of  some 
mines  are  extended  under  the  bed  of  the  sea,  when  of  course 
especial  attention  must  be  paid  to  the  support  of  the  roof  of  the 
mine. 

65.  Perhaps  the  most  remarkable  work  of  this  description  was 
a  mine  opened  more  than  a  century  ago,  in  the  midst  of  the  sea, 
nea   the  port  of  Penzance.     At  low  water  in  this  place  a  gravelly 
bottom  was  left  bare,  in  which  appeared   a  multitude  of  small 
veins  of  tin  ore,  crossing  each  other  in  every  direction.     The  sub- 
jacent strata  also  contained  this  mineral  in  considerable  quanti- 
ties ;  and  works  were  carried  on  in  the  rock  whenever  the  sea, 
the  time,  and  the  season  would  permit,  until  the  depth  became 
too  great. 

66.  The  place  where  this  submarine  tin  ore  was  found  was 
about  two  hundred  yards  from  the  shore ;  and  the  bank  of  the  sea  here 
being  very  steep  and  high,  the  distance  is  considerable,  even  at 
low  water  ;  and  at  high  tide  the  rock  is  covered  by  three  fathoms 
of  water.     As  the  bottom  is  gravelly  and  full  of  rocks,  the  waves 
become  much  agitated,  and  rise  to  a  great  height  when  the  wiijd 
blows  from  particular  points.      This  inconvenience  takes  place 
throughout  the  winter,  and  had  always  led  to  the  failure  of  differ- 
ent attempts  which  had  been  made  before  to  drain  the  mine  and 

What  peculiar  precautions  are  required  in  submarine  mining  ? 

What  instance  of  this  is  particularly  worthy  of  notice  ? 

What  depth  of  water  was  sometimes  found  over  the  Penzance  mine? 


WHEAL  FERRY.  207 

raise  the  ore.  At  low  water-mark,  the  rock  appears  a  little  above 
the  surface  of  the  sea ;  but  during  some  months  of  the  year  it  is 
never  uncovered. 

67.  Against  all  these  difficulties  a   single   individual,  whose 
property  was  not  worth  three  crowns,  and  who  undertook  the 
work  anew,  had  to  contend.     This  courageous  miner  employed 
three  summers  in  sinking  a  pit,  during  which  time  he  could  only 
work  two  hours  a  day,  and  every  time  he  went  to  work  he  found 
his  excavation  full  of  water,  which  he  was  obliged  to  empty  out 
before  he  could  recommence  working;  and  this  occasioned  great 
difficulties  when  he  set  about  blasting  the  rock.      He  therefore 
built  round  the  mouth  of  the  pit  a  turret  of  wood  impervious  to 
water,  or  a  sort  of  coffer-dam,  and  by  this  means  was  able  to  pro- 
long the  time  of  working  on  the  rock.     And  by  raising  the  turret 
above  the  greatest  height  to  which  the  sea  could  reach,  he  endea- 
voured to  keep  out  the  water  entirely. 

68.  But  here   he  had  new  difficulties  to  encounter :    first  to 
make  the  turret  water-tight;  and  secondly,  to  secure  it  in  such  a 
manner  that  neither  the  flux  nor  reflux  of  the  sea,  or  the  shocks  of 
the  waves,  should  overturn  it.     The  rock  was,  fortunately,  of  por- 
phyry ;  not  too  hard  to  cut,  but  still  very  firm.     He  shaped  the 
portions  he  separated  from  it,  a,nd  disposed  them  in  a  regular 
manner  at  the  foot  of  the  turret,  and  closed  and  caulked  with 
oakum  and  fat  cement  all  the  interstices  between  the  wood  and 
the  stone,  so  that  the  whole  was  united  into  one  mass.     The  pit, 
like  all  those  in  Cornwall,  was  lined  with  planks,  all  the  joints 
being  well  caulked  or  pitched.     When  this  frame-work  was  thus 
constructed,  he  supported  it  with  iron  braces.     About  the  mouth 
of  the  pit  he  raised,  upon  four  great  piles,  a  platform  of  planks,  to 
support  the  windlass,  which  was  worked  by  four  men.     When 
with  great  labour  and  difficulty  the  pit  and  tower  were  finished, 
he  then  reaped  the  fruits  of  his  industry,  and  establishing  a  re- 
gular work  at  Stockvvork,  he  drew  from  it  in  a  little  time  a  consi- 
derable quantity  of  tin,  and  put  his  adventure  on  a  good  footing. 

69.  There  were  times,  however,  when  his  undertaking  was  not 
in  so  good  a  state.  To  save  expense  and  diminish  his  labours,  he  at- 
tacked the  part  of  the  mine  overhead,  by  which  means,  at  high 
water,  the  sea  penetrated  through  the  chinks  of  the  rock,  so  that 
he  was  obliged  to  sustain  the  roof,  which  was  pretty  extensive, 
in  some  parts  by  planks  and  thick  props,  to  prevent  the  great  mass 
of  water  which  pressed  on  it  above  from  driving  it  in.     Besides 
this,  notwithstanding  all  his  endeavours,  it  was  not  possible  to 

Jkeep  his  wood-work  water-tight  in  the  winter,  and  when  the  sea 
was  rough,  he  could  not  transport  the  ore  ashore  in  his  boat.  In 

What  expedient  enabled  the  miner  to  obviate  the  difficulty  arising  from 
tho  water  ? 

What  device  enabled  him  to  raise  the  mineral  from  his  submarine 
pit  ? 

What  difficulty  arises  from  the  hydrostatic  pressure  in  excavations  un- 
ier  the  ocean  ? 


208  METALLURGY. 

the  autumn  of  1790,  the  chamber  excavated  in  the  inside  of  the 
rock  had  the  following  dimensions  : 

Greatest  depth 36  feet. 

Depth  to  the  level  of  the  passage     -  26  feet. 

Greatest  diameter  of  the  chamber         -  18  feet. 

Least  diameter        -  3  feet. 

70.  Four  men  in  two  hours  emptied  the  pit  of  water  by  the 
^windlass,  at  the  rate  of  four  tons  in  a  minute,  towards  the  end  of 

which  time,  six  men  drove  it  from  the  bottom  of  the  pit,  and 
poured  it  into  the  passage.  After  drawing  out  the  water,  they 
worked  six  hours  on  the  rock.  From  one  tide  to  another,  they 
raised  about  thirty  sacks  of  ore,  each  sack  containing  fourteen 
gallons,  fifteen-sixteenths  of  which  were  so  rich,  that  they  pro- 
duced one-sixth  of  a  hundredweight  of  tin,  and  one-sixteenth  of  a 
hundredweight  was  procured  from  the  remainder  :  so  that  in  six 
months  they  raised  to  the  value  of  600/.  sterling  of  tin.  As  most 
of  the  ore  was  interspersed  in  a  hard  rock,  difficult  to  pound,  the 
undertaker  had  it  roasted  in  a  common  lime-kiln,  which  answeied 
perfectly  well.  There  had  been  nothing  of  the  kind  done  in  Corn- 
wall before.  This  singular  work  was  known  by  the  name  of 
Wheal  Ferry;  the  persevering  individual  who  planned  and  exe- 
cuted it,  died  at  the  age  of  seventy  years,  in  the  winter  of  1791, 
the  mine  having  in  the  preceding  year  yielded  ore  worth  3000/. 

The  works  thus  ingeniously  constructed,  were  subsequently  de- 
stroyed by  accident,  and  the  mine  was  ruined.* 

71.  In  and  on  every  extensive  mine,  from  one  thousand  to  fif- 
teen hundred  men,  women,  and  children  are  employed.    The  men 
and   the  elder  boys  alone  descend  the  mines  and  work  under- 
ground ;  the  women  break  in  pieces  the  ore  with  hammers,  and  the 
children  pick  and  sort  it.    The  best  ores  are  at  once  broken  small 
by  the  double-handed  hammer,-and  put  to  pile,  being  in  that  state 
merchantable ;  the  inferior  ores  are  broken  by  single-handed  ham- 
mers, and  sorted,  the  poorest  are  committed  to  the  stamps,  which 
are  piles  or  heavy  beams  of  wood,  shod  with  iron,  and  tilted,  or 
raised  and  let  down  alternately,  by  means  of  an  axle  turned  by  a 
water-wheel ;  and  thus  the  ore  is  bruised  so  fine,  that  the  whole 
mass  has,  after  being  washed,  the  appearance  of  slime,  and  in  this 
condition  it  is  sold.f 

How  extensively  was  the  Penzance  mine  excavated? 
What  was  the  ultimate  success  of  the  Wheal  Ferry  ? 
What  number  of  persons  are  commonly  employed  in  Cornwall  about  a 
single  mine  ? 

How  are  the  several  classes  of  persons  respectively  engaged  ? 
Describe  the  several  modes  of  levigating  the  ores  of  copper. 

*  Dr.  Lardner's  Treatise  on  the  Progressive  Improvement  and  Present 
Stale  of  the  Manufactures  in  Metals,  vol.  iii.  pp.  15 — 17. 
t  Phillips's  Outlines,  pp,  207.  208. 


MECHANICAL  ASSAYS.  209 

72.  The  copper  ores  of  Cornwall  are  not  smelted  in  the  county, 
in  which  coal  is  not  found,  but  are  shipped,  generally  at  the  port 
nearest  to  the  mine,  for  Swansea,  in  the  vicinity  of  which  the 
principal  smelting  companies  have  their  establishments.  Formerly 
there  were  one  or  two  companies  which  smelted  in  Cornwall,  but 
it  seems  to  be  found  by  experience  to  be  less  expensive  to  carry 
the  ore  to  the  coal,  than  to  bring  the  coal  to  the  ore.     The  ore  is 
taken  on  the  backs  of  mules  to  the  port,  or  in  carts,  or  in  one  or 
two  instances  by  a  railroad ;  and,  in  return,  coal  is  brought  to  the 
mine,  shipped  from  Wales,  in  vessels  which  take  back  copper  ore. 

Docimasy. 

73.  The  art  of  assaying  minerals,  for  the  purpose  of  ascertain- 
ing their  composition,  and  especially  the  nature  and  proportions 
of  their  metallic  products,  is  termed  docimasy,  or  docimastics.   It 
differs   from   metallurgy  in  its  strictest  acceptation,  in  that  the 
requisite  operations  of  docimasy  are  performed  on  a  small  scale, 
and  without  any  attention  to  those  economical  considerations  which 
are  of  so  much  importance  in  the  processes  of  the  metallurgist. 

7-1.  The  great  object  of  assaying  a  mineral,  is  to  form  an  ac- 
curate estimate  of  its  component  parts  and  their  relative  propor- 
tions, and  thus  to  discover  whether  it  is  rich  enough  in  metal  to 
pay  the  expenses  of  working  a  mine,  and  reducing  the  ore  to  the 
metallic  state.  These  preparatory  operations  are  peculiarly  re- 
quisite, with  regard  to  minerals  or  mineral  products  containing 
the  precious  metals,  because  a  knowledge  of  the  exact  quantity  of 
metal  in  any  substance,  especially  if  the  quantity  be  comparatively 
small,  must  be  obtained  before  it  can  be  possible  to  decide  whether 
it  will  be  worth  while  to  undertake  its  extraction. 

75.  There  are  three  modes  of  conducting  docimastic  operations  : 
(1.)  The  mechanical  assay;  (2.)  The  assay  by  the  dry  method  ; 
(3.)  The  wet  assay. 

Mechanical  Assays. 

76.  Processes  of  this  nature  merely  consist  in  the  separation  of 
substances  mechanically  mixed  in  metallic  ores,  and  are  executed 
by  sifting,  washing,  and  thus  removing  the  soluble  and  lighter 
portions  of  the  substance  to  be  examined,  so  that  the  metallic 
particles  may  be  obtained  in  a  separate  state.     To  make  an  assay 
by  the  mechanical  method,  the  ore  having  been  pulverized,  a  cer- 
tain quantity  of  it,  by  weight,  is  to  be  put  in  a  sieve  with  a  little 
water,  and  then,  by  agitation,  the  lighter  matters  may  be  separated 
from  the  metallic  particles,  in  consequence  of  their  superior  specific 

In  what  manner  do  the  Cornish  miners  dispose  of  their  ore  when  ex- 
tracted ? 

How  does  doeimasy  differ  from  metallurgy  ? 
What  is  the  great  purpose  of  assaying  minerals? 
In  how  many  different  modes  are  assays  conducted  ? 
How  are  mechanical  assays  performed  ? 
s2 


210  METALLURGY. 

gravity.  Thus  a  moist  mass,  or  scfilich,  more  or  less  pure,  will 
be  obtained,  from  which  a  judgment  may  be  formed  of  the  quality 
of  the  ore,  and  from  this  mass  the  whole  of  the  metal  may  be  ex- 
tracted by  assaying  it,  either  in  the  dry  or  in  the  wet  method. 

77.  Washing  is  practised  as  a  method  of  assaying  auriferous 
and  stanniferous  sands,  or  with  regard  to  schlichs,  which  have 
been  already  washed,  to  ascertain  the  degree  of  purity  to  which 
they  have  been  reduced.  This  mode  of  assay  may  be  also  advan- 
tageously employed  to  separate  the  oxide  of  tin,  and  the  sulphurets 
of  lead  and  antimony,  from  the  gangues  or  stony  matter  in  which 
these  ores  are  frequently  disseminated.  The  same  kind  of  assay 
may  be  properly  used  to  discover  whether  scoriae,  or  other  products 
of  the  furnace,  retain  enough  metallic  matter  to  make  it  worth 
while  to  treat  them  on  a  large  scale  by  stamping  and  washing.* 


by  the  Dry  Method. 

78.  The  dry  mode  of  assay  has  for  its  object  the  discovery  of 
the  nature  and  quantity  of  the  metals  contained  in  any  ore  ;  but  to 
prevent  needless  experiments,  it  is  desirable  to  be  able  to  decide 
beforehand  what  metal  may  be  supposed  to  exist  in  a  fragment 
of  an  ore  about  to  be  submitted  to  examination.     To  obtain  this 
previous  information,  attention  should  be  paid  to  mineralogical 
characters,  which  will  often  afford    positive   indications  of  the 
nature  of  the  mineral  ;  but  when  there  is  any  room  for  doubt,  it 
becomes  necessary  to  vary  the  mode  of  inquiry,  and  submit  the 
substance  to  a  twofold  operation.     Thus  the  mineral  fragment  to 
be  assayed  is  to  be  divided  into  two  portions,  one  of  which  may 
be  analyzed  with  a  view  to  discover  the  precise  nature  of  the  metal, 
and  the  other  to  determine  its  proportion  relatively  to  the  other 
substances  with  which  it  is  mixed. 

79.  Assays  by  the  dry  method  require  great  skill  in  the  operator, 
and  but  an  inconsiderable  apparatus.     They  may  be  performed 
generally  in  workshops,  and  they  become  peculiarly  necessary  in 
those  where  ores  are  purchased  fronr  different  localities  ;  because, 
when  the  quantity  of  metal  they  afford  can  be  ascertained,  it  be- 
comes easy  to  fix  the  price  that  must  be  given  for  the  ores.  These 
assays  are  performed  by  submitting  the  mineral  body  to  the  action 
of  fire,  either  by  means  of  cupels,  retorts,  matrasses,  crucibles,  or 
by  the  blowpipe.     It  is  frequently  requisite  in  these  operations  to 
add  a  flux,  or  some  other  substance  which  may  facilitate  the  de- 
composition of  the  ore. 

What  is  meant  by  the  term  schlich  in  mechanical  assaying  ? 
Under  what  different  circumstances  may  the  method  of  washing  be 
adopted  ? 

What  is  the  object  of  assaying  by  the  dry  method  1 
What  two  purposes  are  to  be  answered  by  this  method  ? 
What  are  the  requisites  for  prosecuting  this  mode  of  assaying? 
In  what  way  are  its  processes  executed  ? 

*  Metallurgie  Pratique,  pp.  33,  34. 


USE  OF  THE  BLOWPIPE.  211 

80.  The  blowpipe  is  peculiarly  useful  in  conducting  assays,  in 
consequence  of  its  ready  application,  without  loss  of  time  or 
trouble,  as  it  affords  a  simple  and  convenient  method  of  heating  to 
a  high  degree,  very  quickly,  any  substance  sufficiently  small  to 
be  involved  in  the  flame  excited  by  this  instrument.  There  are  a 
variety  of  forms  of  the  blowpipe,  among  the  most  convenient  of 
which  are  those  of  Dr.  Wollaston,  described  by  Mr.  Brande,* 
and  that  of  the  Swedish  chemist,  Gahn.  This  blowpipe  is  com- 
posed of  four  tubes  :  (1.)  The  principal  tube  or  mouthpiece  of  the 
blowpipe ;  (2.)  A  cylindrical  chamber  to  collect  the  water  formed 
from  condensation  of  the  moisture  of  the  breath  :  (3.)  The  beak, 
at  the  extremity  of  which  is,  (4.)  The  jet-pipe,  through  which  the 
air  escapes.  The  jet  may  be  formed  with  an  opening  more  or  less 
minute,  to  suit  particular  purposes.  This  blowpipe,  when  taken 
to  pieces,  may  be  fitted  into  a  box  or  case,  adapted  to  the  pocket, 
so  that  it  may  be  ready  for  use  in  any  situation. 


d' 


The  accompanying  figure  represents  this  blowpipe,  a  is  the 
main  tube,  to  which  is  sometimes  adapted  an  ivory  mouthpiece,  e, 
to  avoid  the  contact  of  metal  with  the  lips,  b  is  the  flat  cylin- 
drical box,  from  the  convex  side  of  which  projects  the  short  tube 
o,  to  receive  the  end  of  a.  In  one  of  the  flat  sides  of  the  box  is 
fitted,  with  a  swivel  joint,  the  beak  c,  with  its  jet-pipe  c?,  canaMe 
of  revolving  into  any  position  as  indicated  by  d' ' . 

81.  In  employing  this  instrument,  it  must  be  held  in  the  hand 
with, the  larger  end  of  the  tube  introduced  between  the  lips;  then 
the  beak  of  the  jet  being  approached  to  the  flame  of  a  wax  candle, 
or  that  of  a  lamp,  with  a  wick  of  a  proper  size,  on  blowing  through 
the  pipe  the  flame  will   be  projected  upon  the  substance  to  be" 
assayed.     A  large  wax  candle  will  be  found  to  supply  the  best 
flame,  w^iich,  when  urged  by  the  blast,  exhibits  a  double  figure, 
the  internal  flame  being  conical,  blue,  and  well  defined,  and  at  its 
apex  the  most  intense  heat  is  excited ;  the  external  flame,  encom- 
passing the  other,  is  red,  vague,  and  undetermined,  and  much 
infe/rior  in  temperature. 

82.  Some  attention  is  necessary  to  acquire  the  habit  of  properly 
using  the  blowpipe,  so  as  to  throw  the  flame  regularly  and  unin- 

What  circumstances  render  the  blowpipe  peculiarly  serviceable  for  this 
purpose  ?     Of  what  parts  do  ihe  most  approved  blowpipes  consist? 
In  what  manner  is  this  instrument  to  be  used  ? 

*  See  Webster's  Manuel,  on  the  Basis  of  Brando's. 


212  METALLURGY. 

terruptedly  on  the  body  to  be  examined,  and  also  to  continue  the 
blast  during  a  sufficient  time  without  fatigue  and  exhaustion. 
This  object  may  be  attained  by  first  filling  the  mouth  with  air, 
which  is  to  be  driven  through  the  tube  by  the  pressure  of  the 
muscles  of  the  cheeks  alone,  those  of  the  chest  not  at  all  contribut- 
ing to  the  keeping  up  of  the  blast.  To  renew  the  air  in  the  mouth 
it  is  necessary  to  respire  only  through  the  nostrils,  which  may  be 
done  without  discontinuing  the  blast,  and  thus  a  person  may  con- 
tinue blowing  a  long  time  without  inconvenience. 

83.  The  substance  to  be  submitted  to  the  action  of  the  blow- 
pipe, should  not  be  larger  than  a  peppercorn,  and  it  may  be  placed 
on  the  extremity  of  a  slip  of  platina,  or  held  in  a  pair  of  pincers 
of  that  metal,  or  else  laid  in  a  small  cavity  on  the  surface  of  a 
piece  of  charcoal.     In  the  latter  case  the  charcoal  should  not  be 
that  of  fir,  or  any  other  wood  which  would  be  liable  to  sparkle  in 
burning,  and  the  cavity  in  which  the   mineral  is   laid  may  be 
covered  with  another  piece  of  charcoal,  only  leaving  an  opening 
for  the  access  of  the  flame.     In  most  cases,  instead  of  exposing 
the  mineral  merely  to  the  action  of  the  flame  urged  by  the  blow- 
pipe, the  substance  is  pulverized,  and  mixed,  either  with  oil  or 
with  water,  and  some  proper  flux ;  and  a  small  pellet  thus  being 
formed,  is  to  be  submitted  to  the  flame,  and  it  will  thus  be  less 
exposed  to  be  driven  off  when  ihe  action  of  the  fire  becomes  violent. 

84.  When  a  mineral  substance  is  heated  at  the  extremity  of  the 
flame,  on  platina  or  charcoal,  uncovered  and  exposed  to  the  air,  it 
may  become  oxidated;  but  when,  on   the  contrary,  it  is  heated 
without  the  contact  of  air,  which  may  be  done  by  covering  it  with 
charcoal,  or  projecting  the  flame  so  that  it  may  environ  the  body 
on  all  sides,  it  will  become  disoxidated,  either  entirely  or  in  part, 
if  it  contained  oxygen.     The  results  in  either  cases  will  conse- 
quently be  very  different,  for  the  first  is  termed  the  fire  of  oxida- 
tion, and  the  second  the  fire  of  reduction. 

85.  When  it  is  requisite  to  oxidate  a  metallic  substance,  com- 
bined with  any  flux,  it  must  be  heated  intensely,  and  when  fused, 
gradually  withdrawn  from  the  point  of  the  blue  flame,  and  the 
operation  repeated  as  often  as  may  be  necessary,  using  a  jet  of 
large  aperture.     The  oxidation  may  also  be  accelerated  by  the 
addition  of  a  small  quantity  of  nitrate  of  potash.     In  order  to 
reduce  the  metallic  oxides,  the"  glass  bead  formed  by  the  sub- 
stance to  be  examined,  and  the  flux,  must  be  kept  in  fusion  on 
charcoal  as  long  as  it  remains  without  being  absorbed,  that  the 
metallic  particles  may  collect  into  a  globule  on  the  surface  of  the 
charcoal.     It  is  then  to  be  fused  with  a  small  quantity  of  subcar- 

How  is  respiration  to  be  carried  on  while  we  use  the  blowpipe  1 
How  is  the  substance  assayed  by  the  blowpipe  to  be  held  ? 
What  previous  preparation  of  a  mineral  facilitates  its  treatment  with 
the  blowpipe  ? 

What  part  of  the  flame  is  called  the  oxidating  fre  ? 

What  part  the  reducing  or  deoxidating  fire  ? 

In  what  manner  is  a  metal  oxidated  when  combined  with  a  flux  ? 

How  are  the  metallic  oxides  thus  formed  to  be  finally  reduced  ? 


MOIST  METHOD  OF  ASSAYING.  213 

bonate  of  soda,  which  will  be  absorbed  by  the  charcoal,  and  the 
spot  where  the  absorption  has  taken  place  must  be  strongly 
ignited,  by  using  a  tube  with  a  small  aperture.  By  continuing 
the  ignition,  that  portion  of  the  metal  not  before  reduced,  will  be 
brought  to  the  metallic  state,  and  the  process  may  be  quickened 
by  placing  the  globule  on  a  smoky  flame,  so  that  it  may  become 
covered  with  soot. 

86.  The  beads  which  contain  metals  frequently  exhibit  a  metal- 
lic splendour,  especially  if  exposed  to  a  gentle  flickering  smoky 
flame  after  the  intense  heat  has  ceased.     With  a  moderate  heat 
the  metallic  surface  remains,  but  after  a  little  practice  it  may  be 
ascertained  without  difficulty,  whether  any  metal  is  contained  in 
the  body  under  examination.     It  should  be  observed  that  glass 
of  borax  alone  sometimes  assumes,  externally,  a  metallic  lustre. 
When  the  experiment  is  concluded,  and  the  charcoal  become  cold, 
that  part  impregnated  with  the  fused  mass  must  be  cut  out  and 
rubbed  down  with  distilled  water  in  an  agate  mortar,  the  soda 
which  formed  the  flux  will  be  dissolved,  the  charcoal  will  float  on 
the  liquid,  and  may  be  poured  off;  any  of  the  metallic  particles 
remaining  at  the  bottom  may  then  be  examined.     By  this  mode 
of  assay  most  of  the  metals  may  be  reduced.* 

Assays  by  the  Moist  Method. 

87.  When  an  ore  is  examined  by  the  moist  method,  complicated 
processes  sometimes  become  requisite,  for  the  management  of 
which  a  considerable  degree  of  skill  in  chemistry  must  be  ac- 
quired; but  this  method  presents  important  advantages  in  practice. 
The  assay  of  ores,  by  the  moist  mode,  consists  principally  in 
exposing  them  to  the  action  of  acids,  alkalies,  or  neutral  salts, 

nd  when  solutions  have  thus  been  obtained,  the  metals  may  be 
recipitated  by  proper  additions,  and  a  judgment  of  their  nature 
formed  from  the  colour  or  other  sensible  properties  of  the  precipi- 
tates. Thus  metallic  solutions  may  be  analyzed  by  the  applica- 
tion of  tests,  but  in  order  to  discover  the  relative  quantities,  as 
well  as  the  qualities  of  a  mineral,  by  the  moist  assay,  the  metals 
must  be  precipitated  from  their  solutions,  and  the  products  edul- 
corated and  weighed. 

88.  Gold  may  be  tested  by  exposing  it  to  the  influence  of  nitric 
acid,  which  acts  upon  almost  all  other  metals,  but  leaves  the  gold 
untouched. 

For  what  purpose  is  subearbonate  of  soda  employed  in  this  operation? 
Of  what  does  assaying  by  the  moist  method  consist? 
How  are  the  actual  quantities  of  different  ingredients  in  a  mineral  de- 
termined ? 

How  is  the  presence  of  gold  ascertained  ? 

*  For  particular  information  relative  to  the  analysis  of  Alloys  by  Cupel- 
lation,  see  Children's  Essay  on  Chemical  Analysis,  pp.  96—108 ;  and  for 
the  methods  of  making  exact  assays  of  the  more  important  metals,  see 
Metallurgie  Pratique,  pp.  39—66. 


214  METALLURGY. 

Silver  ore  may  be  assayed  by  reducing  a  small  quantity  of  it  to 
fine  powder,  digesting  it  in  nitric  acid,  and  mixing  the  filtered 
liquid  with  a  solution  of  common  salt,  (chloride  of  sodium.)  A 
chloride  of  silver  will  then  be  precipitated,  containing,  when 
dried,  75  per  cent,  of  metal ;  or  the  chloride  may  be  reduced  by 
fusing  it  with  three  times  its  weight  of  subcarbonate  of  soda.* 

89.  Iron  ore  is  sometimes  treated  in  the  moist  way,  in  order  to 
discover  whether  it  contains  phosphorus,  which  would  destroy  the 
malleability  of  the  metal.     In  this  case  the  ore  supposed  to  con- 
tain phosphorus  must  be  mixed  with  one-fourth  of  its  weight  of 
nitrate  of  potash,  and  placed  in  an  earthen  crucible,  which  is  to 
be  strongly  heated  for  half  an  hour;  then  the  mixture,  being  with- 
drawn from  the  crucible,  must  be  lixiviated  with  airmail  quantity 
of  distilled  water  and  filtered  :  the  liquor  obtained  is  now  to  be 
assayed  by  the  following  process :  After  it  has  been  neutralized 
by  nitric  acid,  a  solution  of  chloride  of  lime  is  to  be  poured  over 
it,  and  the  liquor  will  not  become  clouded  unless  a  small  portion 
of  carbonate  of  lime  should  be  formed,  which  must  be  separated 
by  filtration  ;  then  a  little  ammonia  must  be  added,  and  if  a  white 
precipitate  is  formed  in  consequence  of  this  addition,  it  will  be  a 
proof  that  the  ore  contained  phosphorus,  the  white  precipitate 
being  phosphate  of  lime. 

90.  The  analysis  of  copper  ore  by  the  moist  method  is  effected 
by  treating  the  roasted  mineral  with  nitric  acid ;  and  by  adding 
ammonia  in  excess,  the  oxide  of  copper  will  be  dissolved,  and  the 
other  metallic  oxides  partly  precipitated  ;  then  the  alkaline  solu- 
tion of  the  metal,  after  being  filtered,  is  to  be  saturated  by  an 
acid,  and  the  copper  may  be  precipitated  in  the  metallic  state,  by 
plates  of  polished  iron. 

91.  The  moist  method  of  assay  may  be  employed  in  analyzing 
the  ores  of  lead,  and  the  products  of  the  foundries.     The  roasted 
ores  must  be  dissolved  in  nitric  acid  somewhat  lowered,  and  the 
solution  is  to  be  diluted  with  water,  and  precipitated  by  a  suffi- 
cient quantity  of  some  soluble  sulphate,  which  forms  with  the 
oxide  of  lead,  sulphate  of  lead.     The  precipitate  being  washed 
and  dried,  always  contains  sixty-eight  per  cent,  of  metal.    In  thi$ 

How  may  silver  ore  be  assayed  ? 

For  what  purpose  is  iron  assayed  in  the  moist  way  ? 

How  is  the  assay  then  conducted  ? 

What  substance  is  added  to  test  the  presence  of  the  phosphoric  acid  ? 

How  is  the  assay  of  copper  in  the  moist  way  to  be  conducted  ? 

How  is  lead  ore  examined  in  the  humid  way  ? 

How  is  the  quantity  of  lead  which  it  contained  finally  discovered  ? 


,  *  Report  of  Brande's  Left,  on  Mineralog.  Chemistry,  in  Jour,  of  Science, 
vol.  iy.  p.  245.  A  convenient  method  of  producing  chloride  of  silver  is 
mentioned  in  Annales  de  Chimie,  t.  xiv.  p.  319.  Put  the  chloride  into  a 
small  vessel  of  zinc  or  cast  iron,  containing  a  little  water;  and  leaving  it 
there  a  short  time,  if  the  vessel  be  clean,  the  decomposition  will  soon  take 
place,  otherwise  a  little  muriatic  or  sulphuric  acid  may  be  added.  Tho 
metallic  product  may  be  washed  with  muriatic  acid. 


METALLURGY  PROCESSES.  215 

mode  of  assay  the  silver  which  may  be  contained  in  the  ore  will 
also  be  precipitated  in  the  state  of  sulphate.  When  it  is  neces- 
sary to  assay  sulphates  of  lead,  either  alone,  or  mixed  with  other 
substances,  the  muriatic  must  be  employed  instead  of  the  nitric 
acid.* 

92.  Solutions  of  the  various  metals  may  be  tested,  and  their 
nature  ascertained  to  a  certain  extent,  by  observing  the  effects  of 
the  addition  of  certain  bodies  called  reagents,  and  noting  the 
colours  and  other  sensible  properties  of  the  precipitates  thence 
produced.     Thus  tincture  of  nutgalls  turns  the  solution  of  iron 
black,  and  the  solution  of  lead  white,  and  with  other  metallic  so- 
lutions, yields  green,  yellow,  brown,  or  blue  precipitates. f 

Metallurgic  Processes  for  the  Reduction  of  Mineralized  Metals 

93.  The  operations  requisite  for  obtaining  metals  in  a  pure 
state  from  their  several  ores  constitute  the  proper  subject  of  me- 
tallurgy.    The  methods  adopted  for  the  reduction  of  metals,  must 
necessarily  be  varied  according  to  the  nature  of  the  metal  to  be 
obtained  in  any  given  case,  and  that  of  the  substances  with  which 
it  may  happen  to  be  blended.    Hence  a  diversity  of  processes  will 
be  required  even  with  regard  to  a  single  metal.    They  may,  how- 
ever all  be  referred  to  three  kinds,  like  those  of  docimasy,  con- 
sisting of  mechanical  operations,  in  the  dry  way,  or  by  means  of  fire, 
and  operations  in  the  moist  way,  chiefly  by  employing  mineral 
acids.     But  in  almost  all  processes  for  obtaining   metals  from 
their  ores,  the  mechanical  and  chemical  methods  are  more  or  less 
combined  according  to  circumstances. 

94.  Metallurgic  chemistry  includes  the  art  of  forming   com- 
pound metals,  or  alloys,  some  of  which  are  more  serviceable  for 
certain  purposes  than  any  of  the  simple  metals.    This  branch  of 
knowledge  it  will  be  percived,  affords  an  extensive  field  for  re- 
search,presentingto  our  notice  many  subjects  extremely  interesting, 
not  only  to  artists  and  men  of  science,  but  especially  to  all  persons 
engaged  in  the  study  of  mineralogy  and  geology.     In  the  few  re- 
maining pages  to  be  devoted  to  metallurgy,  nothing  more  can  be 
attempted  than  the  introduction  of  some  general  notices  of  the 
processes  employed  in  the  reduction  and  refining  of  the  principal 
metals,  and  in  the  formation  of  the  most  useful  alloys",  such  chiefly 
being  selected  as  may  tend  to  show  the  connexion  between  the 

How  are  sulphates  of  lead  and  of  other  materials  tried  ? 
v    By  what  sensible  properties  are  metallic  ores  often  judged  ? 
What  constitutes  the  peculiar  provincce  of  metallurgy  ? 
Of  how  many  kinds  are  the  processes  employed  in  this  art  ? 
What  does  metallurgy  include  besides  the  reduction  of  ores  ? 

*  Metallurgie  Pratique,  pp.  47,  51,  59. 

t  In  Dr.  Henry's  Elements  of  Chemistry,  vol.  ii.,  is  given  a  table  of  pre- 
cipitates thrown  down  from  metallic  solutions  by  the  following  reagents  ; 
(1.)  Prussiated  alkalies  ;  (2.)  Tincture  of  galls  ;  (3.)  Water  impregnated 
with  sulphuretted  hydrogen  ;  (4.)  Hydrosulphurets. 


216  METALLURGY. 

subject  before  us,  and  the  other  branches  of  science  to  which  this 
volume  relates. 

Reduction  of  Ores  containing  Gold. 

95.  As  gold  is  not  found  mineralized,  or  in  the  state  of  proper 
ore,  but  either  pure,  or  else  combined  with  some  other  metal  to  form 
an  alloy,  the  metallurgic  processes  for  reducing  it  are  in  general 
less  complicated  than  in  most  other  cases.  This  metal  is  derived 
from  two  sources,  being  either  mixed  with  sand,  gravel,  and  earthy 
matter,  in  valleys,  ravines,  and  the  beds  of  rivers,  or  occurring 
in  veins,  and  procured  by  mining,  like  metals  in  general.  The 
modes  of  treatment  requisite  to  procure  gold  in  a  state  of  purity, 
vary  according  to  the  state  in  which  it  is  found  in  the  situations 
just  mentioned. 

96..  Gold  obtained  from  alluvial  soils  in  pellets  or  grains,  may 
be  separated  more  or  less  from  the  substances  by  which  it  is  con- 
taminated by  washing.  This  operation  is  performed  frequently 
on  the  spot  where  it  is  procured.  Thus  the  gold  seekers  some- 
times wash  the  auriferous  sands  in  a  sieve  held  in  the  hand ;  or 
else  use  inclined  tables,  which  being  covered  with  coarse  woollen 
cloth  or  rough  hairy  hides  of  animals,  the  earth  and  sand  taken 
up  in  small  quantities  is  thrown  on  the  table,  over  which  a  stream  of 
water  being  poured  or  conducted,  the  lighter  substances  are  wash- 
ed away,  and  the  particles  of  gold  detained  by  their  superior  weight 
on  the  surface  of  the  cloth  or  skin.  But  this  method  has  the 
inconvenience  of  not  separating  the  heavier  portions  of  gravel 
which  become  entangled  among  the  hair  or  wool,  together  with 
the  metal.  The  gold  thus  obtained  may  be  further  purified,  ac- 
cording to  circumstances,  by  amalgamation  with  mercury,  or  by 
cupellation. 

97.  Gold  is  also  found  pure  in  veins,  but  sometimes  in  a  state 
of  minute  division,  and  so  blended  with  other  bodies,  as  to  require 
various  operations  for  its  extraction.  It  is  thus  procured  in 
Hungary,  and  in  this  case  the  whole  contents  of  the  vein  holding 
small  particles,  or  strings,  or  little  nests  of  native  gold,  are 
brought  to  the  surface,  broken  into  small  pieces,  and  carefully 
sorted  ;  the  grains,  where  perceptible,  being  detached  from  the 
matrix,  which  is  chiefly  quartz.  The  poorer  parts  are  then 
stamped,  by  means  of  wood  shod  with  iron  at  the  lower  ex- 
tremity, worked  b^a  water-wheel,  and  thus  the  ore  is  crushed  to 
a  powder  upon  an  iron  plate.  This  powder  is  damped  by  throw- 
ing water  containing  salt  upon  it;  and  a  quantity  of  mercury  be- 
ing put  into  a  bag  of  porous  leather,  is  forced  through  the  pores, 
and  dropping  on  the  damped  powder  in  a  minutely  divided  state, 
is  kneaded  up  with  it. 

In  what  two  states  is  gold  found  in  nature  ? 

By  what  process  is  gold  from  alluvial  soils  separated  ? 

By  what  methods  are  the  auriferous  soils  washed  ? 

In  what  rock  do  veins  and  masses  of  gold  most  frequently  occur? 


REDUCTION  OF  GOLD.  217 

98.  The  paste  containing  mercury  and  gold  thus  incorporated, 
is  afterwards  heated  in  a  proper  vessel  to  about  the  temperature 
of  boiling  water  for  three  or  four  days  ;  the  mixture  is  then  washed 
carefully,  by  small  parcels  at  a  time,  so  that  the  earthy  particles 
are  washed  off,  leaving  only  the  amalgam  of  mercury  and  gold. 
Part  of  the  mercury  is  then  separated,  by  pressure,  in  a  leathern 
bag,  and  the  rest  is  driven  off  by  distillation,  leaving  behind  the 
gold,  and  also  any  portion  of  silver  with  which  it  may  be  alloyed. 

99.  When  gold  occurs  in  a  matrix,  consisting  of  iron  pyrites, 
galena,  &c.,  in  which  the  gold  exists  in  invisible  particles,  the 
masses  of  ore  are  broken  by  hand   into  small   pieces,  and  then 
placed  beneath  the  stamps  to  be  reduced  to  powder,  which  is  car- 
ried by  a  stream  of  water  to  a  series  of  pits,  in  which  the  heaviest 
particles  subside,  the  lighter  earthy  matter  being  carried  away  by 
the  current.    After  repeated  washings,  the  metallic  parts,  consist- 
ing principally  of  pyrites  and  galena,  are  roasted  in  a  reverberator^- 
furnace,  with  a  proportion  of  quicklime,  at  a  red  heat,  but  not  so 
as  to  fuse  the  mass,  until  part  of  the  sulphur  is  driven  off;  the 
fire  is  then  increased,  and  the  whole  brought  to  a  state  of  thin 
fusion,  and  then  let  out  into  a  mould  of  sand. 

100.  During  the  fusion,  the  iron,  on  account  of  its  strong  affinity 
for  sulphur,  resumes  the  portion  of  which  it  had  been  deprived  by 
previous  roasting,  by  decomposing  the  sulphurets  of  lead,  copper, 
&c.,  with  which  it  is  mixed,  in  consequence  of  which  these 
metals,  by  specific  gravity,  fall  in  drops  through  the  vitreo-ferru- 
ginous  scoriae,  carrying  with  them  the  gold  and  silver,  and  unite 
at  the  bottom  in  a  dense  metallic  mass.     Hence,  the  pig  that  is 
formed  in  the  mould  of  sand,  is  found  to  consist  of  two  parts 
adhering  to  each  other,  but  easily  separable  by  the  hammer;  the 
uppermost  and  largest  portion  is  composed  of  cellular  scoria?,  be- 
neath which  is  a  black  heavy  compact  mass  containing  the  gold 
and  silver,  together  with  lead,  copper,  some  sulphur,  and  iron ; 
this  is  now  broken  into  small  pieces,  and  roasted  and  fused  once 
or  twice  more,  until  the  sulphur  and  other  impurities  are  separated, 
leaving  nothing  but  the  gold,  silver,  lead,  and  copper. 

101.  The  separation  of  gold  from  lead  is  effected  by  cupella- 
tion.     The  cupe'l  or  test  is  a  porous,  infusible,  earthy  mass,  with 
a  hollow  concavity  at  the  top^Sbr  the  reception  of  the  metals  ;  this 
being1  placed  in  a  furnace,  so  as  not  to  be  in  contact  with  the 
burning  fuel,  and  a  current  of  air  at  the  same  time  passing  over 
the  surface  of  the  test,  the  metal  is  brought  almost  to  a  state  of 
ebullition.     At  this  temperature  the  lead  becomes  changed  to  the 
state  of  a  vitreous  oxide,  which,  sinking  into  the  pores  of  the  test, 
leaves  the  gold  behind ;  and  if  the  ore  contained  silver  and  cop- 
In  what  way  is  the  amalgamation  of  gold  conducted? 

How  is  gold  treated  when  combined  with  the  sulphurets  of  iron,  cop- 
per,, or  lead  ? 

How  are  the  lead  and  copper  deprived  of  their  sulphur  ? 

What  separates  the  gold  and  silver  from  the  fused  mass  of  the  ingre- 
dients ?  How  is  gold  separated  from  lead  ? 

T 


218  ^          METALLURGY. 

per,  subsequent  processes  will  be  required  to  effect  their  sepa- 
ration. 

Reduction  of  the  Ores  of  Silver. 

102.  Silver  is  extracted  from  its  ores,  either  by  smelting  in  a 
manner  similar  to  that  practised  with  regard  to  other  metals,  or 
by  amalgamation  with  mercury.     The  processes  carried  on  at  the 
extensive  amalgamation  works  of  Freyberg,  the  capital  of  the 
mining  district  of  Saxony,  and  where  one  chief  advantage  of  this 
mode  over  smelting,  is  the  saving  of  fuel,  are  described   with 
scientific  minuteness  by  J.  H.  Vivian,  Esq.,  in  the  annals   of 
Philosophy,  vol.  xxvii. ;  and  an  abstract  of  this  descriptive  state- 
ment may  be  found  in  the  third  volume  of  Dr.  Lardner's  Treatise 
on  Manufactures  in  Metals. 

103.  Silver  like  gold  frequently  requires  to  be  subjected  to  the 
JP^ocess  of  cupellation,  to   separate    it  from   oxidizable   metals. 

This  method  of  purifying  silver  is  adopted  in  Persia,  and  the 
following  account  of  it  is  given  by  Ostad  Muhammed  Ali,  and 
was  published  in  Brande's  Journal  of  Science : 

104.  Persian    metallurgical  process  for  the  purification  of  sil- 
ver.— A  sort  of  basin  is  made,  either  by  excavating  the  ground, 
or  by  arranging  stones  in  a  circle.     This  is  from  nine  to  twelve 
or  fourteen  inches  wide,  and  is  incomplete  at  the  side  in  one  place, 
for  the  reception  of  the  fuel,  which  by  its  combustion  is  to  melt 
the  metal.    The  fuel  consists  of  two  large  and  long  logs  of  wood, 
which  are  placed  with  their  ends  in  the  aperture  on  the  edge  of 
the  basin.     These  ends  are  lighted  by  placing  on  them  burning 
fuel,  and  then  the  blast  from  a  pair  of  bellows  is  directed  so  as 
to  pass  across  the  fire,  and  thus  drive  the  flame  and  heat  into  the 
basin,  acting  as  a  large  blowpipe.     Lead  containing  silver,  or 
impure  silver  with  the  addition  of  lead,  is   then  placed   in  the 
basin,  and  being  soon  melted  and  heated  by  the  flame,  it  is  puri- 
fied as  by  common  cupellation.     The  litharge  (vitrified  oxide  of 
lead)  is  forced  off  to  the  sides  as  it  is  formed,  and  either  absorbed 
or  lost,  and  as  the  wood  burns  away  before  the  blast  of  air,  the 
logs  are  thrust  onward  until  all  is  consumed ;  then  fresh  logs  are 
supplied,  if  necessary,  or  the  process  stopped,  as  may  be  found 
convenient.  * 

105.  "The  singular  fact  has  been  ascertained,  that  silver  in 
fusion  absorbs  oxygen,  which,  on  solidifying,  it  parts  with;  and 
Gay  Lussac  says  that  it  thus  gives  out  twenty-two  times  its  own 
volume,  and  that  the  presence  of  a  very  little  copper  destroys  this 
property."* 

To  what  process  is  silver  subjected  in  order  to  separate  it  from  other 
metals  ? 

Describe  the  Persian  method  of  purifying  silver. 

What  fact  in  regard  to  the  affinity  of  silver  for  oxygen  has  been  ob- 
served ? 

*  Donovan's  Treatise  on  Chemistry,  p.  241. 


REDUCTION  OF  CRUDE  PLATINA.  219 

The  attraction  of  both  silver  and  copper,  when  in  fusion,  for 
oxygen,  was  observed  several  years  since  by  Mr.  S.  Lucas,  of 
Sheffield,  who  stated  the  result  of  his  observations  in  a  letter  to 
Mr.  Dalton,  published  in  the  Manchester  Transactions.  He  found 
that  silver,  in  a  fluid  state,  absorbed  oxygen,  not  only  from  the 
atmosphere,  but  also  from  other  bodies  which  gave  it  out  when 
heated,  as  some  of  the  nitrates. 

100.  If  silver  in  large  quantities,  after  being  exposed,  when 
melted,  to  a  current  of  oxygen  gas,  or  atmospheric  air,  be  allowed 
to  cool  gradually,  the  surface  first  becomes  solid,  then  soon  bursts, 
ebullition  ensues,  and  an  elastic  fluid  escapes,  driving  before  it  a 
portion  of  the  internal  fluid  metal,  and  causing  protuberances  on 
its  surface.  Substances  which  have  a  strong  attraction  for  oxy- 
gen, placed  in  contact  with  the  melted  metal,  prevent  the  ebullition 
from  taking  place.  Thus  charcoal,  spread  for  a  few  minutes  on 
the  surface  of  the  silver  in  fusion,  absorbs  the  oxygen  which  it 
may  have  acquired,  and  no  escape  of  gas  or  appearance  of  ebul- 
lition then  occurs,  whether  the  metal  be  cooled  slowly  or  hastily.* 

Reduction  of  Crude  Plafina. 

107.  Platina  is  never  mineralized,  but  it  is  often  debased  by 
intermixture  with  other  metals  ;  and  in  the  state  in  \vhich  it  is 
imported  from  South  America,  the  crude  metal  contains  silica, 
mercury,  gold,  palladium,  rhodium,  iridium,  osmium,  iron,  cop- 
per, and  lead,  as  well  as  platina.     This  last  metal  may  be  sepa- 
rated  from   the   other  bodies  by  the  following   process : — The 
mercury  is  to  be  driven  off  by  exposing  the  ore  to  a  considerable 
degree  of  heat,  an  operation  which  renders  the  platina  yellower, 
in  consequence  of  the  appearance  of  grains  of  gold.     The  residue 
may  be  digested  in  nitro-muriatic  acid,  diluted  with  its  bulk  of 
water ;  this  takes  up  gold,  iron,  and  a  little  platina :  if  the  re- 
maining ore  be  now  digested*in  nitro-muriatic  acid,  by  far  the 
largest  portion  will  be  dissolved,  and  there  will  remain  a  black 
powder ;  to  the  nitro-muriatic  solution  add  a  solution  of  muriate 
of  ammonia,  which  will  occasion  the  precipitation  of  the  greater 
part  of  the  platina  in  the  state  of  a  very  difficultly  soluble  ammo- 
nia-muriate, and  which  may  be  separated  upon  a  filter. 

108.  In  the  filtrated  liquor  immerse  a  plate  of  zinc,  which  will 
throw  down  lead,  rhodium,  palladium,  and  a  portion  of  platina; 
the  lead  may  be  separated  by  very  dilute  nitric  acid  :  dissolve  the 
residue  in  nitro-muriatic  acid,  add  common  salt,  and  evaporate  to 

What  occurs  when  a  considerable  mass  of  silver  is  heated  in  contact 
with  oxygen  ? 

What  prevents  the  occurrence  of  this  phgnomer.on  ? 
In  what  state  is  platina  found  ? 
By  what  means  is  it  separated  from  mercury  ? 
How  is  the  platina  next  treated  ? 
How  may  the  nilro-muriate  of  platina  be  decomposed? 

*  Journ.  of  Science,  vol.  iv.  pp.  169,  170. 


220  METALLURGY. 

dryness;  this  residue,  composed  of  the  soda-muriates  of  platina, 
palladium,  and  rhodium,  is  to  be  digested  in  alcohol,  which  dis- 
solves the  triple  salts  of  platina  and  palladium,  but  not  that  of  rho- 
dium, which  therefore  is  thus  separated  :  to  the  alcoholic  solution 
add  solution  of  muriate  of  ammonia,  which  throws  down  ihe 
platina  and  leaves  the  palladium  in  solution,  which  may  after- 
wards be  precipitated  by  ferrocyanate  of  potassa.  The  insoluble 
black  powder,  by  alternate  fusions  with  potassa,  and  boiling  in 
muriatic  acid,  may  be  resolved  into  osmium,  soluble  in  the  alkali, 
and  iridium  in  the  acid. 

109.  The  yellow  precipitates  formed  by  the  addition  of  muriate 
of  ammonia  to  the  alcoholic  solution  of  the  salts  of  platina  and 
palladium,  consisting  of  ammonia-muriate  of  platina,  must  then 
be  collected,  edulcorated  with  warm  water,  and  dried.     It  must 
next  be  distributed  into  saucers,  which  are  to  be  introduced  into  a 
small  oven,  and  exposed  for  a  short  time  to  a  low  red  heat,  in  order  to 
drive  off,  by  sublimation,  the  greater  part  of  the  muriated  ammonia. 
When  withdrawn  it.  will  form  a  spongy  mass  of  a  gray  colour. 
About  half  an  ounce  of  the  platina  in  this  state  is  to  be  put  into 
a  strong  iron  mould,  about  %$  inches  long  by  1^  wide,  and  is  to 
be  compressed  as  forcibly  as  possible  by  striking  with  a  mallet 
upon  a  wooden  pestle,  cut  so  as  accurately  to  fit  the  mould; 
another  half-ounce  is  then  added  and  treated  in  the  same  manner, 
and  so  on  till  six  ounces  have  been  forced  into  the  mould  :  a  loose 
iron  cover,  just  adapted  to  fit  into  the  mould,  is  then  laid  upon 
the  platina,  and  by  means  of  a  strong  screw-press,  almost  every 
particle  of  air  is  forced  out  from  the  metal.     This  is  an  important 
part  of  the  process ;  for  if  any  quantity  of  air  is  left  in  the  mass, 
the  bar  into  which  it  is  formed  will  be  liable,  in  the  subsequent 
operations,  to  scale  and   be  full   of  flaws.     The  pressure  being 
duly  made,  the  mould  is  to  be  taken  to  pieces,  and  the  platina 
will  be  found  in  the  form  of  a  hard*  compact  parallelepiped. 

110.  It  is  now  to  be  placed  in  a  charcoal  forge  fire,  and  exposed 
.to  the  most  intense  white  heat,  in  order  completely  to  drive  off 

the  remaining  ammoniacal  muriate ;  this  being  done,  it  is  to  be 
quickly  placed  on  a  clear,  bright  anvil,  and  gently  hammered  in 
all  directions  with  a  clean  hammer.  This  must  be  repeated  several 
times ;  after  which  the  mass  will  be  perfectly  compact,  and  fit  to 
be  laminated  or  wrought  in  any  other  manner  that  may  be  required. 

Reduction  of  the  Ores  of  Mercury. 

111.  The  metallurgic  treatment  of  mercury  is  very  simple,  and 
the  metal  is  extracted  chiefly  by  two  methods.     The  following  is 
the  process  adopted  in  the  Palatinate.     The  ore  is  to  be  sorted, 

For  what  purpose  is  alcohol  used  in  this  assay  ? 

How  is  the  ammonia-muriate  of  platina  brought  to  the  state  of  spongy 
platina  ? 

Does  the  process  of  melting  form  any  part  of  the  reduction  of  platina? 
What  is  the  purpose  of  compressing  the  spongy  mass  ? 


REDUCTION  OF  THE  ORES  OF  IRON.  221 

pulverized,  and  mixed  with  quicklime  or  slaked  lime ;  and  the 
richer  it  is  in  metal,  so  much  greater  must  be  the  proportion  of 
the  lime.  The  mixture  is  then  introduced  into  large  cast-iron 
retorts,  which  are  placed  in  two  ranks,  one  above  the  other,  in  a 
long  furnace ;  and  each  retort  is  to  have  attached  to  it,  without 
luting,  a  glass  receiver,  one  third  part  filled  with  water.  The  fur- 
nace is  then  to  be  heated,  at  first  gently,  to  drive  off  the  moisture  ; 
after  which,  the  juncture  of  the  vessels  must  be  closed  with  tem- 
pered clay,  and  a  full  red  heat  is  to  be  applied  for  seven  or  eight 
hours.  The  lime  will  combine  with  the  sulphur  contained  in  the 
mercurial  ore,  and  the  metal  will  be  volatilized  and  condensed  in 
the  receiver.  A  different  method  of  proceeding  is  practised  at 
Almaden  and  at  Idria,  where  furnaces  of  a  peculiar  construction 
are  used,  and  the  reduction  of  the  metal  is  effected  by  the  oxida- 
tion and  consequent  separation  of  the  sulphur,  which  forms  sul- 
phurous acid,  while  the  mercury  is  sublimed,  and  becomes  con- 
densed within  the  apparatus.* 

Reduction  of  the  Ores  of  Iron. 

112.  This  metal  being  found  in  a  state  of  nature,  variously 
combined,  different  processes  are  requisite  to  reduce  it  to  the 
metallic  state.     The  smelting  of  iron  is  a  subject  of  national  im- 
portance, and  hence  it  has  not  only  occupied  much  of  the  attention 
of  writers  on  metallurgy,  but  it  has  likewise  furnished  a  topic  for 
distinct  and  sometimes  voluminous  treatises.     It  can  here,  how- 
ever, be  but  slightly  noticed,  as  our  limits  will  only  admit  of  some 
brief  and  general  statements  of  the  peculiar  methods  of  reducing 
this  metal.    Carbonaceous  matter  of  some  kind  is  always  largely 
employed  in  smelting  iron  ores ;  in  some  countries,  as  Sweden, 
charcoal  is  used  for  that  purpose ;  while  in  Great  Britain,  there 
are  but  few  charcoal  furnaces,  coke  being  generally  employed 
instead  of  it.     The  most  abundant  of  the  iron  ores  is  the  common 
ironstone,  which  is  an  impure  carbonate  of  the  metal,  found  in 
small  lumps  or  layers  in  the  clay  which  separates  the  beds  of  coal. 

113.  The  ore  is  first  reduced  to  pieces  about  the  size  of  an  egg, 
and  is  sometimes  roasted  in  cup-shaped  kilns,  having  lighted  coal 
at  the  bottom,  on  which  the  iron  ore  is  heaped  so  as  to  fill  the 
kiln,  and  the  roasting  is  generally  complete  by  the  time  the  coal 
is  consumed.     More  commonly,  however,  the  roasting  is  per- 
formed on  the  ground  :  a  bed  from  four  to  eight  inches  in  thickness 
ofvcoal  is  first  laid  down,  on  which  is  placed  a  layer  of  broken  iron- 
stone, from  eighteen  inches  to  two  feet  thick  ;  two  inches  of  small 

In  how  many  ways  is  mercury  reduced  from  its  native  state  ? 

What  is  the  purpose  of  employing  lime  in  this  process  ? 

Plow  is  the  reduction  of  mercury  effected  at  Idria? 

What  kind  of  matter  is  extensively  employed  in  reducing  iron  ores  ? 

*  See  Metallurgie  Pratique,  pp.  296--302. 

T2 


222  METALLURGY. 

coal  are  then  laid  on  the  ore,  and  on  this  a  pile  of  ore,  diminishing 
in  size  so  as  to  form  a  ridge  at  the  top,  and  the  whole  is  then 
covered  with  small  coal  and  coal-dust.  The  pile  is,  at  bottom, 
from  thirty  feet  to  sixty  yards  long,  ten  to  sixteen  feet  wide,  and 
about  five  feet  high.  The  lower  stratum  of  coal  is  then  lighted, 
which,  by  degrees,  lights  the  whole  mass.  In  a  few  days  the 
ironstone,  when  cool,  becomes  of  a  red  or  reddish-brown  colour; 
and  the  sulphur,  carbonic  acid,  water,  and  inflammable  matter 
being  driven  off,  it  is  fit  for  the  smelter. 

114.  In  England  and  Wales  the  furnace  in  which  iron  is  smelted 
is  upwards  of  forty  feet  high,  and  is  built  of  the  strongest  masonry, 
externally  of  the  form  of  a  truncated  four-sided  pyramid,  inter- 
nally of  a  peculiar  figure,  and  lined  partly  by  fire-bricks  and  partly 
by  sandstone;  and  into  which,  when  charged,  air,  in  a  high  state 
of  compression,  and  sometimes  previously  heated,  is  forced.    This 
is  a  blast  furnace,  and  is  charged  at  the  chimney  at  regular  in- 
tervals with  coke,  iron  ore,  and  limestone,  in  the  proportion  of 
about  4  of  the  first,  3£  of  the  second,  and  1  of  the  third  by  weight; 
and  is  always  kept  so  charged  to  a  certain  height. 

115.  In  somewhat  more  than  forty-eight  hours  the  whole  runs 
down,  being,  however,  constantly  replaced  by  fresh  materials,  and 
the  iron  being  melted,  is  suffered  to  flow  out  once  in  eight,  ten,  or 
twelve  hours,  into  furrows  made  in  sand,  where  it  forms  pig  iron  ; 
or  into  a  large  reservoir,  whence  it  is  poured  by  means  of  ladles 
into  moulds,  forming  all  the  various  articles  of  cast  iron  ware, 
from  cannon  and  steam-engine  boilers  to  fire-grates  and  common 
iron  pots. 

116.  The  fuel  for  smelting  iron  hitherto  used  in  the  United 
States,  is  charcoal,  but  few  attempts  having  been  made  to  intro- 
duce any  other.     The  abundance  of  wood  has  thus  far  allowed 
this  employment  of  its  product ;  but  the  vast  extension  recently 
given  to  the  iron  business,  now  calls  for  the  introduction  of  some 
more  economical  species  of  combustible.     The  process  of  cok- 
ing is  about  to  be  carried  on  to  considerable  extent,  at  the  iron 
works  on  the  west  branch  of  the  Susquehanna  river,  in  Pennsyl- 
vania, and  the  advantage  which  would  result  from  the  employ- 
ment of  anthracite  for  this  object,  has  called  forth  a  number  of 
ingenious  attempts  to  adapt  its  action  to  the  reduction  of  iron  ore. 
In  connexion  with  charcoal  it  has  been  used  to  some  extent  in 
France,  but,  as  it  seems,  without  any  decided  advantage,  at  least 
in  the  place  where  it  was  applied,  over  the  fuel  previously  employ- 
ed.    In  England  coke  has  long  since  almost  entirely  superseded 
charcoal,  and  within  the  last  three  or  four  years  raw  bituminous 
coal  has  in  many  works  nearly  taken  the  place  of  coke. 

v 

In  what  two  modes  is  the  roasting  of  iron  ore  effected  ? 
What  is  the  height  and  general  construction  of  smelting  furnaces  ? 
What  are  the  proportions  of  coke,  ore,  and  limestone  ?    In  what  length 
of  time  is  the  entire  charge  of  a  high  smelting  furnace  run  out? 
What  fuel  is  chiefly  used  for  smelting  iron  in  the  United  States  ? 
What  varieties  of  fuel  have  been  employed  in  Europe  ? 


SMELTING  FURNACE. 


223 


117.  Turf  and  even  wood  have  in  some  instances  been  advan- 
tageously substituted  for  a  part  of  the  usual  charge  of  charcoal, 
in  a  smelting  furnace.     The  hot  air  blast  is  one  of  the  most  recent 
and  capital  improvements  in  the  smelting  process  ;  and  the  intro- 
duction of  this,  together  with  a  change  from  the  exclusive  use  of 
charcoal  to  a  partial  use  of  wood,  has  been  found  by  M.  Naher, 
at  the  iron  works  at  Plons,  Canton  of  St.  Gall,  Switzerland,  to 
give   decided  advantages  over  the  method   previously  pursued. 
The  economy  of  using  a  hot  blast  with  charcoal  alone,  was  chief- 
ly in   the  diminution  of  the  quantity  of  fuel  required  by  a  given 
weight  of  pig  metal,  being  about  fifteen  per  cent.,  while  the  ac- 
tion of  the  furnace  was  retarded  by  -J-  of  its  original  number  of 
charges  per  day  when  using  charcoal  only,  and  fed  with  cold  air ; 
but  the  substitution  for  one  half  the  bulk  of  charcoal  of  an  equal 
bulk  of  dry  pine  wood,  not  only  gave  more  pig  metal  in  a  given 
time  than  when  using  charcoal  alone,  but  increased  the  yield  of 
the  furnace  from  1560  to  2019  Ibs.  in  twelve  hours. 

118.  The  hot  air  blast  is  applied  by  carrying  the  pipe  from  the 
bellows,  sometimes  through  a  hot  air  chamber  above  the  top  of  the 
tunnel  head  of  the  smelting  furnace,  in  .order  to  economize  that 
part  of  the  heat  which  ordinarily  escapes  and  is  lost.     At  other 
times  it  passes  through  a  long  hot  air  chamber,  expressly  intended 
for  heating  the  air,  and  supplied  with  hot  gas  from  furnaces  of  its 
own  ;  the  latter  arrangement  is  seen  in  the  annexed  figure,  in  which 
a  plan  of  the  smelting  furnace  at  the  level  of  the  tuyeres  is  given. 


H  is  the  hearth  or  receptacle  for  the  melted  iron.  A  A  A  A  are 
the  parts  of  the  masonry  of  the  structure.  C  C  C  are  three  branch 
pipes  coming  from  the  main  bellows  pipe,  b  b  are  small  furnaces, 
placed  near  the  termination  of  the  respective  branches.  B  is  a 
larger  furnace  under  the  main  pipe.  W  is  a  water  regulator  by 
which  the  intensity  of  the  blast  is  prevented  from  exceeding  a 
given  amount.  G  is  a  common  chimney  for  the  escape  of  gas 
from  all  the  air  heating  furnaces. 

What  is  found  to  be  the  advantage  of  using  hot  air  in  a  blast  furnace 
for  smelting  iron? 

What  has  experience  proved  in  regard  to  the  use  of  wood  for  the  same 
purpose  ?  What  is  the  arrangement  for  heating  air  for  this  purpose  ? 


224  METALLURGY. 

119.  There  are  several  varieties  of  iron  to  be  found  in  com- 
merce, the  most  important  of  which  are  cast  iron,  wrought  iron, 
and  steel.     Of  cast  iron  there  are  two  principal  kinds,  called  re- 
spectively white  and  gray  iron.  White  iron  is  very  hard  and  brittle, 
and  exhibits  a  radiated  fracture,  being  composed  of  a  congeries  of 
laminae,  variously  aggregated.     Acids  act  upon  it  but   slowly. 
Gray  or  mottled  iron  is  softer  and  less  brittle  than  white,  so  that 
it  admits  of  being  bored  or  turned  in  a  lathe.    The  texture  of  the 
metal  gives  it  the  appearance  of  bundles  of  minute  fibres. 

120.  Cast  iron,  after  having  been  in  some  degree  refined  by 
fresh  fusion,  in  contact  with  charcoal,  is  converted  into  wrought 
iron  by  a  process  called  puddling.     The  cast  iron  is  put  into  a 
reverberatory  furnace,  and  when  in  the  state  effusion  it  is  agitated, 
so  that  every  part  of  the  mass  may  be  exposed  to  the  air  and  flame. 
After  some  time  the  melted  metal  heaves,  a  blue  flame  issues 
from  its  surface,  it  gradually  grows  tough,  loses  its  fusibility  and 
becomes  pulverulent.     The  fire  is  then  increased,  so  that  the  parti- 
cles again  agglutinate  at  a  welding  heat,  and  are  wrought  np  into 
separate  masses,  which,  while  intensely  heated,  are  passed  suc- 
cessively between  rollers,  and  a  quantity  of  carbonaceous  matter 
being  pressed  out,  the  metal  is  rendered  malleable.   The  flattened 
masses  cut  in  pieces  are  then  placed  in  parcels  in  a  reverberatory 
furnace,  strongly  heated,  and  again  hammered  or  rolled  out  into 
bars.     The  iron  is  thus  rendered  more  tough,  flexible,  and  mal- 
leable, but  at  the  same  time  almost  infusible,  and  in  this  state 
it  appears  to  be  nearly  pure. 

121.  A  bar  of  wrought  iron,  when  its  texture  is  examined,  dis- 
plays a  fasciculated  appearance,  the  fibres  extending  longitudi- 
nally, as  may  be  perceived  in  a  bar  of  wrought  iron  that  has  been 
torn  asunder.     Steel  is  a  compound  of  iron  and  carbon,  the  latter 
in  small  proportion,  and  it  is  not  improbable  but  it  may  also  con- 
tain silicon.     It  partakes,  to  a  certain  extent,  of  the  properties  of 
cast  iron  and  wrought  iron,  being  fusible,  like  the  former,  and 
malleable,  like  the   latter.     When    it   is   heated   and    suddenly 
cooled,  it  becomes  hardened,  and  by  proper  management  it  may 
thus  be  variously  tempered  to  form  cutting  instruments,  and  for 
other  purposes. 

122.  When  steel  is  kept  for  along  time  hi  a  state  effusion,  its 
carbon  is  dissipated,  and  it  becomes  reduced  to  the  state  of  pure 
iron.   Iron  is  converted  into  steel  by  a  process  termed  cementation  ; 
which  consists  in  submitting  iron  with  charcoal  in  alternate  lay- 
ers to  the  action  of  heat  in  a  close  furnace  for  several  days.   Cast 
steel  is  prepared  by  melting  common  steel  in  a  crucible,  with  a 
flux  composed  of  carbonaceous  and  verifiable  ingredients.     It  is 
still  more  highly  carbonized  than  common  steel,  as  well,  as  more 
brittle  and  fusible ;  and  being  harder,  of  more  uniform  texture,  and 

How  is  wrought  iron  made  ?    What  is  steel  ? 
How  is  it  hardened  ? 

How  may  steel  be  converted  into  malleable  iron  ? 
How  is  cast  steel  prepared  ? 


REDUCTION  OF   THE  ORES  OF  TIN.  225 

of  more  compact  grain,  it  is  adapted  for  all  the  finest  articles  of 
cutlery. 

123.  Iron  in  the  process  of  its  conversion  into  steel  acquires  a 
blistered  surface,  and  in  this  state  it  is  used  for  some  purposes 
under  the  name  of  blistered  steel.     This,  when  made  into  smaller 
bars  and  hammered,  forms  tilled  steel,-  which  when  broken  up, 
heated,  welded,  and  again  drawn  out  into  bars,  forms  shear  steal. 

Reduction  of  the  Ores  of  Tin. 

124.  The  ore  from  which  tin  is  procured  in  England  is  an  oxide, 
found  interspersed  through  some  parts  of  the  mineral  veins  in 
Cornwall,  in  small  crystals,  accompanied  by  masses  of  slate  or 
granite,  sulphurets  of  iron  and    copper,  and    arsenical   pyrites, 
quartz,  and  occasionally  tungstate  of  iron  and  other  minerals.     It  is 
commonly  blasted  by  gunpowder,  and  brought  to  the  surface  in 
pieces  of  considerable  size,  which  are  stamped  to  a  fine  powder,  till 
the  ore  has  the  appearance  of  slime,  and  it  is  afterwards  washed  on 
a  wooden  frame  termed  a  huddle;  the  stream  of  water  carrying 
off  the  lighter  earthy  particles,  and  leaving  the  more  weighty 
grains  of  tin,  which,  after  repeated  washings,  are  reduced  to  a 
state  fit  for  the  smelting-house. 

•  125.  Being  still  mingled  with  other  substances,  it  is  in  this  state 
termed  black  tin.  This  is  roasted  at  a  low  red  heat,  in  a  rever- 
beratory  furnace,  to  volatilize  the  arsenic  and  sulphur.  It  is  then 
of  an  ochrey  red  colour,  owing  to  the  oxidation  of  the  iron  and 
copper.  It  is  again  washed,  and  the  impurities  separated  from  it; 
and  it  is  then  reduced  by  placing  it  in  a  reverberatory  furnace, 
about  seven  feet  long  arid  three  and  a  half  wide,  from  seven  to 
fifteen  hundred  weight  of  the  roasted  ore  being  mixed  with  about 
one-fifth  of  small  coal,  and  in  some  cases  a  small  quantity  of  slaked 
lime,  the  whole  being-  turned  over  and  moistened  with  water;  a 
brisk  fire  is  then  applied  for  about  six  hours,  the  tin  sinking,  as 
it  becomes  reduced  to  the  bed  of  the  furnace,  beneath  a  surface 
coating  of  boiling  black  scoriae.  The  furnace  is  then  tapped,  and 
the  melted  tin  suffered  to  flow  into  a  small  cavity  at  the  foot  of 
the  furnace.  When  that  is  done,  the  scoriae  are  raked  off,  and 
a  new  charge  of  roasted  tin  ore  and  small  coal  thrown  in. 

126.  When  the  metal  in  the  pit  is  red-hot,  it  throws  up  a  quantity 
of  slag,  very  rich  in  metal,  which  is  immediately  returned  into  the 
furnace;  and  when  the  melted  tin  is  become  sufficiently  cool,  it  is 
taken  out  with  iron  ladles  and  poured  into  moulds  of  granite, 
where  it  consolidates,  each  charge  affording  on  an  average  from 

What  is  meant  by  blistered  steel  ? 

What  by  tilted  steel  ? 

What  is  shear  steel  ? 

In  what  state  is  the  ore  of  tin  found  ? 

How  is  the  earthy  matter  separated  ? 

What  is  black  tin  ? 

How  many  processes  are  necessary  to  bring  it  to  the  state  of  pure  metal  ? 


226  METALLURGY. 

four  to  five  hundredweight  of  metal.  The  melted  tin  thus  pro- 
cured is  next  placed,  without  any  addition,  in  a  small  reverbera- 
tory  furnace,  and  exposed  to  a  very  gentle  heat ;  the  purest  part 
which  melts  first  is  drawn  oif,  forming  the  common  grain  tin ;  the 
more  refractory  part,  containing  a  small  and  variable  proportion  of 
copper  and  arsenic,  is  then  melted  and  cast  into  pigs  of  common 
tin,  or  block  tin. 

127.  The  finest  grain  tin,  however,  is  procured  from  the  stream- 
tin  ore,  so  termed  because  it  consists  of  the  loose  crystals  of  oxide 
of  tin  found  in  the  nibble  or  alluvial  soil  in  some  of  the  low 
grounds  of  Cornwall,  having  been  washed  thither  by  streams  of 
water.    These  are  free  from  the  impurities  of  vein-tin  ore,  and  the 
metal  is  consequently  more  perfectly  reduced,  and  by  more  simple 
processes. 

Reduction  of  the  Ores  of  Copper. 

128.  The  copper  ore,  from  which  the  metal  is  generally  pro- 
cured, is  the  yellow  sulphuret,  a  combination  of  copper  with  sulphur 
nnd  iron.     The  next  ore  which  occurs  most  abundantly  is  the  sul- 
phuret, containing  about  eighty  per  cent,  of  copper.    The  oxides, 
carbonates,  and  arseniates  of  copper,  are  also  found,  but  in  smaller 
quantities,  and  they  are  of  less  importance.      Both  arsenic  and 
sulphur  adhere  strongly  to  copper ;  and  as  a  small  proportion  of 
either  renders  the  metal  brittle  and  difficult  to  work,  peculiar  at- 
tention is  necessary  in  the  reduction  of  copper  ore,  in  order  that 
these  substances  may  be  separated. 

129.  The  reduction  of  copper  ore  is  completed  by  means  of  eight 
processes.     The  first  is  that  of  calcining  in  a  reverberatory  fur- 
nace, about  17  feet  by  19,  with  a  bottom  or  bed  made  of  fire-bricks. 
The  chimney  is  from  40  to  50  feet  high,  which  causes  such  a 
powerful  draught  that  the  arsenic  and  sulphur,  separated  in  roast- 
ing the  ore,  pass  almost  wholly  through  the  chimney  into  the  open 
air.    About  three  tons  of  the  ore  aro  spread  over  the  bottom  of  the 
furnace,  being  thrown  in  at  the  top,  through  a  kind  of  funnel  or 
hopper.     The  fuel  is  small  coal,  which  is  burnt  at  the  anterior 
part  of  the  furnace,  and  its  flame  passes  over  the  surface  of  the 
ore  in  its  passage  to  the  chimney. 

130.  In  this  furnace,  which  is  called  the  calcining  furnace,  the 
ore  is  roasted,  without  addition,  with  a  dull  red  heat  for  twelve 
hours,  being  frequently  stirred  with  a  long  iron  rake,  to  expose 
fresh  surfaces  to  the  action  of  the  flame.     The  ore  is  not  melted 
here;  but  when  roasted  sufficiently  to  oxidate  the  iron,  and  con- 
In  what  sort  of  moulds  are  the  pigs  of  tin  cast  ? 

What  is  meant  by  grain  tin  ? 
How  is  the  best  kind  of  this  tin  obtained  ? 

From  what  kind  of  copper  ores  is  the  greatest  portion  of  that  metal  ob- 
tained ? 

What  effects  have  arsenic  and  sulphur  on  the  qualities  of  copper  ? 
How  many  processes  are  required  to  effect  the  reduction  of  copper  ore  ? 
How  is  the  ore  disposed  for  calcination  ? 


REDUCTION*  OF  THE  ORES  OF  COPPER.  227 

vert  the  sulphur  into  sulphurous  acid,  jt  undergoes  the  second  pro- 
cess, namely,  that  of  being  melted  ;  and  for  this  purpose  is  car- 
ried to  another  furnace,  about  11  feet  by  8,  and  here  it  receives  a 
fusing  heat,  but  still  without  any  addition,  except  a  little  slag, 
or,  when  the  ores  are  very  sullen,  a  little  fluor  spar  to  assist  the 
fusion. 

131.  When  the  ore  is  melted,  the  liquid  mass  is  well  stirred, 
and  afterwards  the  slag  is  raked  from  its  surface.     More  calcined 
ore  is  then  added,  and  when  the  furnace  is  full  it  is  tapped,  and 
the  melted  metal  flows  into  an  adjoining  pit  full  of  water,  by 
which  means  it  becomes  granulated.    The  metal  in  this  state  con- 
tains about  one-third  of  copper,  and  consists  of  copper,  sulphur, 
andiron.     Five  charges  are  melted  in  twenty-four  hours.     In  the 
third   operation,  the'  granulated  metal  is  calcined  to  oxidate  the 
iron,  and  it  remains  twenty-four  hours  in  the  furnace;    during 
which  it  is  often  stirred  and  turned  about,  the  heat  being  at  first 
moderate,  but  gradually  increased. 

132.  The  fourth  process  is  that  of  melting,  after  calcination,  in 
the  small  furnace,  some  slags  from  the  last  operation  being  added, 
and  pieces  of  furnace  bottoms  impregnated  with  metal  in  the  form 
of  oxide  of  copper,  which  become  reduced  during  this  process ; 
the   oxygen  of  the   copper  combining  with  the  sulphur  passes 
off  as  sulphurous  acid  gas,  while  the  reduced  metal  enters  into 
combination  with  the  sulphuret.     The  slags  being  skimmed,  the 
melted  metal  is  either  tapped  and  suffered  to  run  into  water,  where 
it  is  granulated,  or  else  into  sand  beds,  where  it  becomes  solid. 
Its  produce  in  fine  copper  is  now  about  60  per  cent. 

133.  The  fifth  process  is  that  of  again  subjecting  the  metal  to 
the  same  mode  of  calcination  as  in  the  third  process.  The  sixth  pro- 
cess consists  in  the  melting  again  of  the  metal,  as  in  the  fourth 
process,  and  the  result  is  a  coarse  copper,  containing  from  80  to  90 
per  cent,  of  pure  metal.     In  the  seventh  process  the-  Dpetal  is 
roasted  in  the  smaller  furnace,  chiefly  to  oxidate,  and  -finally  to 
expel  the  volatile  substances.     From  25  to  30  per  cent,  of  metal, 
by  this  process,  becomes  fused  at  the  end  of  the  operation,  which 
continues  from  twelve  to  twenty-four  hours,  according  to  circuni- 

. stances.  The  metal  is  then  tapped  into  sand  beds,  and  the  pi^ ; 
in  this  state  are  termed  blistered  copper.  It  is  now  fit  for  the  re- 
finery. 

131.  The  eighth  process  is  that  of  refining  or  toughening.  This 
appears  to  be  a  delicate  process,  the  success  of  which  depends  on 
several  circumstances  that  are  judged  of  principally  by  the  eye  of 
the  workman.  It  is  conducted  in  a  furnace  similar  to  that  for 
melting;  and  the  chief  objects  appears  to  be  that  of  abstracting 

How  for  melting  and  granulating? 

How  for  separating  the  iron  ? 

What  is  the  purpose  of  the  fourth  process  ? 

What  of  the  fifth  ? — the  sixth  ? — the  seventh  ? 

What  is  blistered  copper  ? 

How  is  the  refining  pro^e^s  conducted  ? 


228  METALLURGY. 

from  the  nearly  pure  metal  the  last  portions  of  oxygen,  which  is 
effected  by  adding  charcoal  to  the  metal  while  in  fusion,  and  stir- 
ring it  occasionally  with  a  pole  of  birch-wood,  until  the  operator 
judges  it  to  be  pure 

Reduction  of  Ore  of  Lead. 

135.  The  principal  part  of  the  lead  procured,  is  derived  from  the 
ore  called  galena,  which  is  a  sulphuret  of  lead.    Other  ores,  as  the 
carbonate,  the  sulphate,  and  the  oxide  of  lead,  are  occasionally 
mixed  with  the  galena,  which  also  frequently  contains  some  silver, 
and  when  the  quantity  is  sufficient  to  pay  for  the  expense  of 
separating  it,  that  process  is  effected  by  exposing  the  roasted  sul- 
phuret to  the  action  of  air  and  heat,  in  shallow  earthen  dishes. 
The  lead  thus  becomes  oxidated,  or  converted  into  litharge  ;  while 
the  silver  is  left  behind,  retaining  the  metallic  form.  The  litharge 
is  afterwards  reduced  by  fusing  it  with  charcoal. 

136.  In  the  usual  process  for   the  smelting  of  lead  ore,  the 
galena  being  freed  by  the  hand  and  the  hammer  from  all  such  im- 
purities as  can  be  readily  separated  from  it,  is  beaten  into  small 
pieces,  and  after  repeated  washings  and  cleansings,  is  placed  in  a 
reverberatory  furnace  at  a  low  red  heat  for  some  hours,  to  drive 
off  the  sulphur  and  arsenic,  without  fusing  the  lead ;  and  when 
the  flame  on  the  surface  has  changed  from  blue  to  a  reddish  white, 
the  roasting  is  considered  as  finished,  the  lead  being  converted 
into  an  oxide. 

137.  The  reverberatory  furnace  commonly  used  is  about  10  feet 
long  and  6  feet  wide  internally,  and  about  2j  feet  deep  ;  the  fire- 
place being  at  one  end,  from  which  the  flame  rises  into  the  fur- 
nace. The  quantity  of  ore  usually  thrown  into  the  furnace  at  once 
is  sixteen  hundred  weight,  of  one  hundred  and  twenty  pounds  each, 
which  quantity  is  spread  over  the  floor  of  the  furnace,  and  the 
doors  are  then  closed. 

138.  The  roasting,  as  above  mentioned,  being  completed  in  a 
moderate  heat,  a  small  quantity  of  charcoal  is  added,  the  doors 
closed,  and  the  reduction  completed  ;  the  lead,  in  a  reduced  state, 
lying  at  the  bottom  of  the  furnace,  covered  by  a  slag  two  or  three 
inches  in  thickness,  the  slag  is  then  tapped  and  runs  off,  and  is 
used  for  mending  the  roads.     Some  quicklime,  in  powder,  is  now 
thrown  down  upon  the  metal  in  a  state  of  fusion,which  serves  to  raise 
and  cake  the  remaining  slag ;  which,  by  means  of  a  rake,  is  taken 
from  the  surface,  and  is  nearly  black,  and  very  heavy.     The  lead 
is  then  suffered  to  run  out  of  the  furnace  into  a  pan,  and  the  scum 
or  dross  being  taken  from  the  surface  is  thrown  back  into  the  fur- 

From  what  species  of  ore  is  lead  generally  obtained? 
How  may  silver  be  separated  from  an  ore  of  lead  ? 
In  what  manner  is  litharge  reduced  to  pure  metal? 
What  is  the  common  process  for  reducing  galena  ? 
What  kind  of  furnace  is  employed  ? 
What  use  is  made  of  the  scoriae  from  this  process? 


REDUCTION  OF  THE  ORES  OF  ZINC.  229 

nace :  the  lead  is,  lastly,  ladled  from  the  pan  into  iron  moulds, 
and  left  to  cool.  All  these  operations  are  repeated,  by  means  of 
two  sets  of  workmen,  during  every  seven  or  eight  hours. 

Reduction  of  the  Ores  of  Zinc. 

139.  The  ore  of  zinc,  whether  calamine  or  blende,  is  first  broken 
into  small  pieces,  and  the  galena,  pyrites,  and  other  impurities 
are  separated  as   exactly   as   possible   by  the   hand ;  it  is  next 
calcined  at  a  moderate  red  heat  in  a  reverberatory  furnace,  by 
which  the  calamine  is  freed  from  its  carbonic  acid,  or  the  blende 
from  most  of  its  sulphur.  It  is  then  washed,  by  which  the  lighter 
earthy  parts  are  separated  from  the  metallic  oxide,  which  latter 
being  dried  is  well  mixed  with  one-eighth  its  weight  of  charcoal, 
by  ^grinding  the  ore  and  charcoal  together  in  a  mill,  as  a  prepara- 
tion for  smelting. 

140.  The  furnace  in  which  the  reduction  is  performed,  is  of  a 
circular  figure,  somewhat  like  that  of  a  glasshouse  ;  in  it  are  fixed 
six  large  earthen  pots  or  crucibles,  about  four  feet  high,  nearly  of 
the  shape  of  oil-jars ;  into  the  bottom  of  each  crucible  is  inserted 
an  iron  tube,  that  passes  through  the  arched  floor  of  the  furnace, 
and  dips  into  a  vessel  of  water  placed  beneath,  while  the  other 
end  of  the  tube  rises  inside  the  crucible,  to  within  a  few  inches  of 
its  top.   These  crucibles  are  filled  up  to  the  level  of  the  tube  with 
the  mixture  of  roasted  ore  and  charcoal,  the  cover  of  each  is  very 
accurately  luted,  and  the  furnace  is  charged  with  fuel,  by  which 
an  intense  heat  is  kept  up  for  several  hours.     The  zinc,  as  it  is 
reduced,  ascends  to  the  top  of  the  pot  in  the  form  of  vapour,  and 
being  prevented  from  escaping  by  the  closely  luted  cover,  it  de- 
scends through  the  central  iron  tube  into  the  water,  and  is  con- 
densed in  small  drops  or  globules,  which  are  afterwards  melted 
and  cast  into  ingots. 

141.  Common  zinc  generally  contains  a  little  lead,  copper, 
arsenic,  iron,  manganese,  and  probably  plumbago,  which  often 
considerably  impairs  the  quality  of  the  alloys  into  which  it  enters. 
In  order  to  get  rid,  in  part,  at  least,  of  these  impurities,  the  com- 
mon practice  is  to  melt  the  zinc  in  a  crucible,  and  then  to  stir  into 
it,  by  means  of  a  stick  or  earthen  rod,  a  mixture  of  sulphur  and 
fat;  the  latter  of  these  preserves  the  zinc  from  oxidation,  while 
the  former,  uniting  with  all  the  metals  present,  except  the  zinc, 
converts  them  into  sulphurets,  which,  rising  to  the  top,  form 
scoriae  that  may  be  skimmed  off;  this  is  to  be  repeated  as  long  as 
?.ny  scoriee  appear  on  the  surface. 

What  mechanical  process  is  necessary  to  prepare  the  ores  of  zinc  ? 
What  furnace  is  employed  to  effect  the  calcination  of  this  ore  ? 
Describe  the  furnace  in  which  the  reduction  of  zinc  ore  is  effected. 
In  what  manner  and  in  what  form  does  the  metal  make  its  escape  from 
the  melting  pots  ? 
How  is  zinc  purified  from  other  metals  ? 


230  METALLURGY. 

142.  The  only  metals  which  have  been  extensively  applied 
to  purposes  of  utility  in  the  reguline  or  metallic  state,  are  those, 
the  modes  of  reducing  which  have  been  described  in  the  preceding 
pages.     Besides  these,  however,  the  metals  called  nickel,  palla- 
dium, and   rhodium,  have  recently  been  employed  by  artists,* 
though  only  to  a  very  limited  extent;  and  antimony,  arsenic,  and 
bismuth,  though  not  used  alone  in  the  arts,  yet  serve  by  their 
combinations  with  certain  other  metals  to  form  valuable  alloys. 

143.  Gold  in  a  state  of  absolute  purity  is  so  soft  and   pliable, 
that  though  it  possesses  a  high  degree  of  tenacity,  it  is  by  no 
means  so  well  adapted  for  technical  purposes  as  some  of  its-alloys. 
The  addition  of  copper  to  this  metal  renders  it  much  harder  than 
before,  and  gives  it  a  deeper  colour.     Silver,  on  the  contrary, 
communicates  to  gold  a  lighter  tint;  and  the  mixed  metal  met 
with  in  commerce  called  "gilded  ingots,"  consisting  of  silver 
alloyed  with  a  little  gold,  is  as  white  as  pure  silver.     The  gold 
coin  of  most  European  nations  contains  silver  or  copper,  or  both 
those  metals.     The  standard  or  sterling  gold  of  England  is  com- 
posed of  twenty-two  carats, f  or  parts  of  pure  gold,  and  two  of 
copper,  which  proportions  appear,  from  the  experiments  of  Mr. 
ITatchett,  to  form  the  best  alloy  for  the  purposes  to  which  it  is 
appropriated,  resisting  the  influence  of  friction  better  than  any 
other  which  had  been  tried.     Besides  jewellers'  gold,  which 
ought  to  be  of  the  new  standard,  or  eighteen  carats  fine,  alloys  of 
almost  every  degree  of  deterioration  are  used  for  making  trinkets 
and  other  articles. 

144.  "  The  permanence  and  beauty  of  gold  renders  it  a  very 
desirable  ornament,  while  at  the  same  time  its  extensibility  ena- 
bles us  to  use  it  where  its  expense  and  weight  would  otherwise 
preclude  its  employment.     Where   gilding   is   performed   upon 
metallic  surfaces,  it  is  usually  done  by  a  solution  or  amalgam  of 
gold  in  quicksilver.    This  is  called  water  gilding,  and  the  process 
exhibits  an  instance  of  chemical  attraction,  and  subsequent  de- 
composition by  heat.     Steel  is  sometimes  gilded  by  the  ethereal 
solution  of  gold.t 

What  effect  on  the  usefulness  of  gold  is  produced  by  alloying  it  wilh 
copper  ?  What  proportion  of  pure  gold  is  contained  in  the  alloy  used  by 
jewellers  ?  How  is  water-gilding  performed  ? 

*  See  Treatise  on  Chemistry,  Nos.  412  and  457. 

t  The  mode  of  computation  by  carats,  with  reference  to  the  alloys  of  the 
precious  metals,  has  long  been  employed  in  England.  Every  mass  of  al- 
loyed gold  is  supposed  to  be  divided  into  twenty-four  carats,  and  the  rela- 
tive quantity  of  gold  it  contains  is  denoted  by  the  number  of  carats  of  that 
metal  in  the  mass  ;  as  gold  of  twenty-two  carats,  or  standard  gold  for  coin  ; 
gold  of  eighteen  carats,  or  gold  of  the  new  standard,  used  for  watch-cases, 
&c.  This  method  does  not  so  conveniently  admit  of  the  appreciation  of 
various  quantities  of  alloy,  as  that  adopted  in  France,  where  the  pure  gold 
in  alloys  is  estimated  by  thousandth  parts ;  thus  gold  of  eighteen  carats, 
or  containing  £  of  alloy,  would  by  the  French  method  be  said  to  be  of  the 
standard  expressed  by  "750. 

I  Brande's  Lect.  on  Mm.  Chern.  in  Journ.  of  Science,  vol.  iv-  p.  212. 


ALLOYS  OF  TIN".  231 

145.  Silver  forms  useful  alloys  with  copper,  especially  for  coin 
and  plate.     The  addition  of  a  small  proportion  of  copper  to  silver 
renders  the  metal  harder  and  more  sonorous,  without  materially 
impairing  its  colour.     The  silver  coin  of  the  United  States  con- 
tains for  every  12  ounces  of  coin  10  ounces  14  pwts.  4^  grains 
of  pure  silver,  and   1   ounce,  5  pwts.   19T8^  grains  of  copper. 
Copper  is  plated  with  silver  for  various  purposes,  and  by  means 
of  different  processes.     These  metals  may  be  united  by  a  mode 
resembling  the  operation  of  welding;  a  plate  of  silver  being  ap- 
plied to  the  surface  of  one  of  copper,  and  the  mass  compressed 
by  passing  it  between  steel  rollers;  after  which  it  may  be  worked 
into  different  forms  for  use  or  ornament.     An  inferior  kind  of 
plated  copper  is  formed  by  applying  to  the  surface  of  that  metal 
an  amalgam  of  silver,  and*  the  mercury  being  driven  off  by  heat, 
the  surface  is  burnished.     The  brass  dials  of  clocks,  and  the 
scales  of  barometers  and  thermometers,  are  silvered  on  the  surface 
by  rubbing  over  them  a  mixture  of  chloride  of  silver,  chalk,  and 
pearlash. 

146.  The  compounds  of  mercury  with  other  metals  are  called 
amalgams.     That  of  tin  is  extensively  used  for  silvering  (as  it  is 
termed)  looking  glasses.     For  this 'purpose  tin-foil  is  spread  on  a 
flat  stone,  and  covered  with  mercury ;  the  glass  is  then  placed 
upon  the  metallic  surface,  and  the  excess  of  mercury  being  pressed 
but,  the  remainder  amalgamating  with  the  laminated  tin  adheres 
to  the  glass,  forming  on  the  opposite  side  of  it  a  brilliant  reflect- 
ing surface.    An  amalgam  of  bismuth  2  parts,  lead  and  tin  1  each, 
and  mercury  4  parts,  is  used  for  silvering  the  interior  of  hollow 
glass  globes.     This  is  effected  by  introducing  into  the  globe  a 
small  quantity  of  the  metallic  alloy,  which  is  to  be  melted  by 
immersing  the  globe  in  hot  water ;  and  then  by  turning  it  gradually 
in  all  directions,  the  bright  coating  will  adhere  to  the  inside  of 
the  glass.    Zinc,  amalgamated  with  mercury,  forms  a  composition 
which  increases  the  electrical  energy  of  glass  excited  by  friction ; 
and  it  is  therefore  applied  to  electrical  machines. 

147.  Tin  constitutes  the  basis,  or  enters  into  the  composition. 
of  various  useful  alloys.     An  extremely  important  application  of 
this  metal,  which  has  been  carried  to  high  perfection  in  modern 
times,   is   the   coating  of  other  metals.     Copper  vessels   thus 
covered  seem  to  have  been  certainly  in  use  among  the  Romans, 
and  there  is  reason  to  believe  that  they  also  knew  how  to  apply 
tin  in  the  same  manner  to  the  surface  of  iron.     The  process 
of  tinning  iron,  or  making  tin-plate,  consists  chiefly  in  dipping 

What  qualities  of  silver  are  affected  by  alloying  it  with  copper? 

In  what  manner  is  copper  plated  with  silver? 

How  are  clock  faces  and  thermometer  scales  vvhilcned  ? 

How  is  the  silvering  of  looking  glasses  effected  ? 

How  are  globular  mirrors  formed  ? 

For  what  purpose  is  amalgam  employed  in  electrical  experiments  'i 

For  what  purpose  is  tin  extensively  employed  in  the  arts  ? 


232  METALLURGY. 

sheets  of  iron  into  a  vessel  of  melted  tin,  the  surface  of  which  is 
prevented  from  oxidation  by  being  covered  with  melted  tallow. 
The  tin  thus  unites  with  the  opposite  surfaces  of  the  iron,  forming 
with  it  an  alloy  to  a  slight  depth.  Various  precautions  and  mani- 
pulations are  requisite  to  ensure  the  complete  success  of  the  ope- 
ration, and  conduct  it  in  the  most  economical  manner,  of  which 
ample  information  may  be  found  in  a  valuable  paper  on  the  manu- 
facture of  tin-plate,  by  Mr.  Samuel  Parkes.* 

148.  The  process  of  tinning  the  interior  of  copper  vessels  for 
culinary  purposes  is  effected  on  similar  principles.     The  copper 
surface  is  first  polished,  and  then  coated  with  sal  ammoniac  and 
pitch,  to  prevent  oxidation,  and  the  vessel  being  heated,  the  tin 
finely  divided,  and  also  heated,  is  applied  to  it,  and  adheres  to  its 
superfices.     The  composition  of  bronze  used  by  the  ancients  in 
casting  medals,  figures  in  relief,  and  for  other  purposes,  is  not 
exactly  known ;  and  it  is  probable  that  different  kinds  of  alloy  were 
used  by  artists  in  different  countries,  and  for  various  purposes. 
Tin  and  copper,  however,  appear  to  have  been  the  chief,  if  not 
the  sole  constituents  of  this  alloy ;  and  compounds  of  those  metals 
are  still  employed  for  works  of  an  analogous  description. 

149.  Pewter  is  said  to  be  an  alloy  of  tin  and  copper,  containing 
1  part  of  copper  to  20  of  tin ;  but  the  composition  of  this  sub- 
stance is  extremely  variable.    Common  pewter  consists  of  cheaper 
materials,  being  formed  of  80  parts  of  tin  and  20  of  lead ;  while 
the  finest  pewter  has  been  stated  to  contain  about  12  parts  of  tin 
and  1  of  antimony,  with  a  small  portion  of  copper.     Britannia 
metal,  now  frequently  used  for  making  teapots,  spoons,  and  other 
articles,  forming  a  cheap  substitute  for  silver,  much  resembles  the 
last  mentioned  sort  of  pewter.     Its  composition  has  been  thus 
stated :  The  best  block  tin  3£  cwt.,  antimony,  28  lb.,  copper  and 
brass,  of  each,  8  lb. 

150.  Speculum  metal,  a  brilliant  alloy,  used  for  the  construc- 
tion of  concave  mirrors  for  reflecting  telescopes,  is  another  alloy 
into  the  composition  of  which  tin  always  enters,  thoagh  its  chief 
constituent  is  copper.     The  grand  object  in  the  formation  of  this 
substance  is  to  obtain  a  reflecting  body  which  shall  yheld  a  single 
distinct  image,  have  hardness  to  admit  of  its  being  highly  polished, 
and  a  surface  as  little  as  possible  liable  to  become  tarnished  by 
air  and  moisture.     Various  metallic  combinations  have  been  em- 
How  is  tin  plate  manufactured  ? 

How  is  copper  tinned  ? 

Of  what  materials  is  bronze  composed 

What  are  the  ingredients  of  pewter? — Britannia  ware? 

Of  what  are  the  mirrors  for  reflecting  telescopes  composed  ? 

What  are  the  great  purposes  to  be  attained  in  this  case  ? 


*  See  Journ.  of  Science,  vol.  viii. ;  Memoirs  of  the  Manchester  Philoso- 
phical Society,  N.  S.,  vol.  iii. 


ALLOYS  OF  COPPER.  233 

ployed  for  these  purposes,  by  different  artists  and  experimental 
philosophers,  among  which  it  will  be  sufficient  to  mention  the 
alloy  of  1  part  tin  and  2  of  copper,  recommended  by  Mr.  Madge; 
and  the  more  complex  metal  formed  of  copper  32  parts,  tin  15  or 
16  parts,  and  brass,  arsenic,  and  silver,  each  1  part, 

151.  Lead  when  alloyed  with  other  metals  seems  to  impair 
their  tenacity,  while  it  renders  them  more  fusible.  The  most  use- 
ful of  its  alloys  is  type-metal,  composed  of  about  16  parts  lead, 
and    1  antimony  and  copper;  but  the  proportions,  if  not  the  in- 
gredients themselves,  differ  in  different  foundries,  a  good  deal  of 
secrecy  being  observed  with  respect  to  the  methods  of  forming 
this  compound.     The  chief  object  in  the  combination  must  be  to 
obtain  complete  fusibility,  so  that  when  cast  the  type  shall  be  per- 
fect, forming  an  ex-act  counterpart  of  the  matrix  ;  and  likewise  that 
the  letters  may  be  hard  enough  to  wear  well,  and  stand  their  work 
firmly,  having  just  so  much  tenacity  as  to  break  rather  than  bend, 
when  under  the  application  of  great  force.     An  alloy  of  lead  and 
antimony  is  also  used   to  majte   plates  on  which  music  is   en- 
graved. 

152.  Copper  forms  various  valuable  alloys,  the  most  important 
of  which  is  brass,  in  which  it  is  combined  with  zinc.     This  alloy 
is  usually  produced  by  mixing  granulated  copper  with  calamine 
(ore  of  zinc)  and  charcoal,  and  exposing  the  mixture  to  a  degree 
of  heat  sufficient  to  reduce  the  ore,  and  the  revived  zinc  uniting 
with  the  copper  in  a  state  of  fusion,  the  melted  alloy  is  cast  into 
plates.     The  proportions  of  the  respective  metals  employed  are 
variable,  constituting  different  kinds  of  brass  :  but  it  usually  con- 
tains from  12  to  18  percent,  of  zinc,  according  to  Brande;  though 
Dr.  Thomson  found,  in  the  valuable  alloy  called  Dutch  brass,  70 
parts  of  copper  and  30  of  zinc.  Pinchbeck,  Prince  Rupert's  metal, 
Dutch  gold,  tombac,  and  similor,  are  alloys  composed  of  copper 
and  zinc,  the  proportion  of  the  latter  metal  being  smaller  than  in 
brass,  and  hence  they  are  formed  by  the  addition  of  copper  to 
brass.     Tutenag  is  said  to  be  an  alloy  of  copper  with  zinc  and  a 
little  iron.     In  a  metallic  substance  called  white  copper,  brought 
from    China,    Dr.    Fyfe   found,   besides   the   three   metals    just 
mentioned,  a  large  proportion  of  nickel. 

The  following  table  contains  a  view  of  the  composition  and  ap- 
plication of  a  number  of  the  most  useful  alloys  employed  in  the  arts; 
it  is  principally  due  to  ihe  labours  of  Messrs.  Chaudet,  of  Paris, 
and  P.  N.  Johnson,  of  London,  and  is  condensed  from  a  table, 
communicated  for  the  Journal  of  the  Franklin  Institute,  by  Mr.  F. 
Peale. 

What  are  some  of  the  proportions  observed  in  making  type  metal  ? 

What  effect  has  lead  on  the  melals  with  which  it  is  mixed  ? 

How  is  brass  manufactured  ? 

What  is  the  composition  of  Dutch  brass? 

What  is  thai  of  tutenag  ? 

What  ingredients  have  been  found  in  white  copper? 

*  See  Jour.  Frank.  Inst.  vol.  xvi.  p.  219. 
u  2 


234  METALLURGY. 

Talk  of  Alloys,  Solders,  and  Amalgams,  used  in  the  Arts. 

Alloy  of  Gold  Coin.— (Fr.  Stand.)  Gold  900,  Cop.  100. 
"  Silver  Coin.— (Fr.  Stand.)  Sil.  900,  Cop.  100. 
"  Gold  Coin.— (U.  S.  Stand.)  Gold,  899.22,  Cop.  and 

Sil.  100.78. 

"       Silver  Coin.— (U.  S.  Stand.)  Sil.  892.43,  Cop.  107.57. 
"       Gold  Coin.— (Eng.  Stand.)     Gold,  916.67,  Cop.  and 

Sil.  83.33. 

"       Silver  Coin.— (Eng.  Stand.)    Sil.  925,  Cop.  75. 
"       "  Billon." — (Fr.  Stand.)   Cop.  800,  Sil.  200. 
"       Gold  Medals — (Fr.  Stand.)     Gold,  916,  Cop.  84. 
"       Bronze  Medals.*    Cop.  920,  Tin  80. 
"       Jewellery.— (Fr.  Stand.)    Gold  750,  Cop.  250. 
"       Silver  Plate.— (Fr.  Stand.)    Sil.  950,  Cop.  50. 
"       Imitation  of  Gold.    Cop.  905.5,  Tin  94.5. 
"       Imitation  of  Silver.— (Park.)     Cop.  578.0,  Zinc  271.5, 

Nick.  142.7,  Lead  7.7. 
"  '    Cannon.     Cop.  900.9,  Tin  99.1. 
"       Statues,  sometimes  lead  and  zinc.     Cop.  914.0,  Zinc 

55.3,  Tin  17.0,  Lead  13.7. 
"       Bronzes  and  Candelabras.    Cop.  784.8,  Zinc  172.2,  Tin, 

28.7,  Lead  14.3. 

"       Mounting  of  Fire  arms.    Cop.  800,  Zinc  170,  Tin  30. 
"       Cymbals,f  Tarn  Tarns,  or  Chinese  Gongs.      Cop.  800, 

Tin  200. 

*4       Bells.     Cop.  750,  Tin  250. 
"       Reflectors  of  Telescopes.     Cop.  6G6£  Tin  333£. 
"       Brass  for  the  Lathe4     Cop.  658.0,  Zinc  318.0,  Lead, 

21.5,  Tin  2.5. 

*'       Brass  for  the  Hammer.    Cop.  701,  Zinc  299. 
"       Types.§  Lead  800,  Antim.  200. 
"       Fusible  in  boiling  Water.     Bism.  500.0,  Lead  312.5, 

Tin,  187.5. 
"       For  Plugging  Teeth,  fusing  at  } 

169°.    Bism.    454.5,   Lead  V8  B-f  5  L+3T+1  M. 

284.1,  Tin  176.5,  Mer.  90.9.  _) 
"       For  Tinning  Iron.   Tin  888.9,  Iron  111.1. 
"       Ductile  Gold  of  18  carats,  or  950  mllliemes.||    Cop.  990, 

Gold  10. 

*  The  medals  made  from  this  alloy  have  the  advantage  of  being  struck 
by  a  few  blows  of  the  press,  and  of  wearing  a  long  time. 

"t  This  alloy  is  very  hard;  it  is  annealed  by  dipping,  while  red-hot,  into 
water,  and  is  then  malleable  ;  whilst,  if  suffered  to  cool  gradually,  it  is 
excessively  hard  ;  this  important  fact  is  due  to  M.  d'Arcet,  who  has  thus 
furnished  the  means  of  fabricating,  in  France,  cymbals,  &c.,  formerly  im- 
ported, at  great  cost,  from  China. 

\  The  proportions  indicated  in  this  alloy  having  been  found  by  analysis,  il 
is  evident  that  the  tin  is  present  by  accident 

§  Sometimes  a  small  quantity  of  copper  is  added  to  these  two  metals. 

il  The  previous  combination  of  the  alloy  is  found  to' produce  ductile  gold, 
when  the  same  metals  would  prove  the  contrary  if  mixed  directly. 


TABLE  OF  ALLOYS,  &C.  USED  IN  THE  ARTS.      235 

"       Bells  of  Mantel  Clocks.    Cop.  750,  Tin  250. 

"       Pivots  of  Artificial  Teeth.  Plat.  Sil.  proportions  unc. 

««  Do.*  do.         and  Philosophical  Instruments. 

Pallad.  500,  Sil.  500. 
"       Springs  of  Artificial  Teeth.f    Pallad.  312.5,  Sil.  312.5, 

Cop.  312.5,  Iron,  62.5. 
Solder  for  Gold  of  750,  or  18  carats.  Gold  of  750,  666.7,  Cop.  166.6, 

Sil.  166.6. 

"         Silver  of  750.    Sil.  666$,  Brass  333£. 
"         Brass.    Cop.  500,  Zinc  500. 
"         Lead.    Lead  666#,  Tin  333£. 

Amalgam  of  Gold  for  Gilding  on  Metal.     Mer.  900,  Gold,  100. 
"        of  Silver.     Mer.  850,  Sil.  150. 

"        for  taking  impressions  of  Seals. £     Cop.  and  Mer.  unc. 
"        for  Silvering  Mirrors.    Tin  700,  Mer.  300. 
"        for  Silvering  Globes  of  Glass.     Mer.  800,  Bism.  200. 
"        for  the  Cushions  of  Electrical  Machines.      Mer.  500, 

Tin  250,  Zinc  250. 

*  This  alloy  is  extremely  important ;  it  is  used  for  all  those  purposes  in 
the  fabrication  of  philosophical  instruments,  for  which  platinum  was  for- 
merly applied,  being  superior  to  it  in  hardness  and  colour,  and  yet  inoxida- 
ble  under  all  the  usual  circumstances. 

t  This  is  an  extremely  useful  alloy,  having  a  degree  of  elasticity  only 
exceeded  by  steel,  with  all  the  advantages  of  superior  lightness  and  hard- 
ness over  platinum  ;  this,  and  the  preceding,  are  due  to  Mr.  Percival  N. 
Johnson,  of  London. 

t  This  amalgam  is  hard,  and  melts  at  a  low  heat ;  it  was  used  by  the 
French  police,  under  the  administration  of  the  celebrated  Fouche,  for  the 
purpose  of  opening  and  resealing  the  letters  that  passed  through  their  hands. 


Works  in  the  Department  of  Metallurgy. 

Gray's  Operative  Chemist,  article,  metals. 

Library  of  Useful  Knowledge,  Treatise  on  Manufacture  of  Iron. 
Lardner  on  Manufactures  of  Iron. 
Bigelow's  Technology,  p.  384.  et  seq. 
Bakewell's  Introduction  to  Geology. 

Ure's  Chemical  Dictionary,  various  articles  on  Ores  and  the 
particular  metals. 

Parke's  Chemical  Essays.     2  vols.  8vo. 

Journal  of  the  Franklin  Institute. 

Metallurgie  Pratique. 

Dumas  Traite  de  Chimie  applique  aux  Arts. 

Karsten  on  the  Manufacture  of  Iron,  (French  edition.) 

Annales  des  Mines,  passim. 


MINERALOGY. 

1.  THE  object  of  this  science  is  to  describe  the  general  compo- 
sition, characters,  varieties,  forms,  and  combinations  of  mineral 
bodies.     A  mineral  may  be  described  as  a  substance  destitute  of 
organization  and  vitality,  found  on  the  surface  of  the  earth,  or  im- 
bedded at  various  depths  beneath  it,  in  veins  or  strata,  which  are 
worked  for  the  extraction  of  such  substances,  by  excavations, 
called  mines.     Mineralogy  maybe  distinguished  from  chemistry, 
as  relating  to  the  forms  and  properties  of  certain  bodies  as  they 
are  presented  to  us  by  nature  ;    while  the  latter  science  instructs 
us  how  Vo  procure  a  multitude  of  artificial  products,  derived  alike 
from  the  animal,  vegetable,  and  mineral  kingdoms,  and  to  explore 
their  properties,  especially  as  it  respects  their  modes  of  combina- 
tion.    Mineralogy  is  likewise  to  be  distinguished  from  geology, 
with  which,  however,  it  is  intimately  connected.  ^ 

2.  It  is  the  province  of  the  geologist  to  investigate  the  general 
structure  of  the  earth,  and  the  nature  and  arrangement  of  the 
great  masses  of  which  it  is  composed.     The  mineralogist,  on  the 
other  hand,  confines  his  attention  to  individual  portions  of  unor- 
ganized matter,  distinguished  by  peculiar  and  specific  characters. 
In  the  study  of  geology  it  is  of  the  utmost  importance  to  be  ena- 
bled to  examine  the  objects  of  research,  in  situ  ,•  and  to  ascertain 
their  relative  connexion  and  arrangement,  in  the  formation  of  rocks, 
mountains,  plains,  subterraneous  strata,  and,   in  general,  of  all 
the  great  masses,  the  assemblage  of  which  constitutes  the  solid 
shell,  or  exterior  surface  of  the  terrestrial  globe.     The  nature  and 
properties  of  minerals  may  be  investigated  and  ascertained,  with- 
out any  reference  to  the  situations  in  which  they  are  produced. 

3.  Thus  connected  as  mineralogy  is  with  chemistry,  on  the  one 
hand,  and  with  geology  on  the  other,  it  displays  features  suffi- 
ciently distinct  from  those  of  either;  yet,  at  the  same  time,  the 
objects  of  these  sciences  so  far  correspond,  that  a  complete  know- 
ledge of  mineralogy  cannot  be  obtained  without  a  previous  ac- 
quaintance with  chemistry;  nor  can  the  information  which  these 
sciences  united  afford,  relative  to  the  unorganized  productions  of 
nature,  be  applied  to  a  more  exalted  purpose  than  that  of  aiding 
our  researches  concerning  geology.*, 

What  is  the  object  of  the  science  of  mineralogy  ? 
In  what  points  does  this  science  differ  from  chemistry? 
How  is  it  distinguished  from  geology  ? 
How  is  unorganized  matter  regarded  by  the  mineralogist? 
Is  the  locality  of  a  mineral  of  any  importance  in  the  decision  of  its  cha- 
racter? 

*  The  necessity  of  exact  mineralogical  knowledge  to  the  geologist  lias 
been  very  justly  and  forcibly  expressed  by  Mr.  Aikin  in  the  introduction 
to  his  Manual  of  Mineralogy,  published  in  1815.  He  says  :  "The  absolute 
necessity  of  extreme  accuracy  in  discriminating  one  species  of  mineral 

236 


CLASSIFICATION  OF  MINERALS.  237 

4  Mineral  substances  may  be  discriminated  from  each  other  by 
their  mode  of  crystallization  or  aggregation,  and  the  optical  pro- 
perties depending  on  their  peculiar  forms ;  by  their  physical  charac- 
ters, as  colour,  lustre,  transparency,  hardness,  consistency,  density, 
or  specific  gravity ;  as  also  in  some  cases  by  their  taste  or  odour, 
by  their  relations  to  electro-magnetism,  and  finally  by  their 
chemical  constitution. 

5.  Any  or  all  of  these  various  qualities  and  affections  may 
be  taken  into  consideration  in  forming  classical  arrangements 
of  bodies  belonging  to  the  mineral  kingdom  of  nature.  Hence 
a  diversity  of  systems  and  arrangements  have  been  contrived 
by  various  mineralogical  writers.  But  those  who  have  been 
engaged  in  such  theoretical  speculations,  have  succeeded  so 
indifferently  that  a  distinguished  professor  of  mineralogy,  in  his 
remarks  on  the  state  of  the  science  in  England,  says  : — "  The  value 
of  a  method  of  classification  seems  to  be  looked  upon  as  a  point 
not  worth  discussing; — any  one  method  is  considered  as  good  or 
as  bad  as  any  other.  This  opinion,  indeed,  is  openly  maintained  by 
some  of  our  best  mineralogists.  Their  labours  have  been  em- 
ployed solely  and  exclusively  in  the  crystallographical  and  che- 
mical analysis  of  particular  species  ;  land  I  am  not  aware  that  any 
attempt  has  been  made,  among  us,  to  establish  any  proposition  in- 
cluding a  class  of  species  of  minerals,  with  the  exception  of  Sir 
David  Brewster's  optical  researches."* 

&_  But  on  the  continent  of  Europe  the  case  is  widely  different; 
a  number  of  mineralogical  systems  having  been  published  of  late 
years  in  Germany,  France,  and  Sweden ;  some  of  them  founded 
on  the  chemical  constitution  of  minerals,  some  on  their  crystallo- 
graphical or  other  physical  properties,  and  others  which  may  be 
called  mixed  systems  of  classification,  depending  on  a  combined 

In  how  many  different  ways  may  minerals  be  distinguished  from  each 
other  ? 

Whence  has  arisen  the  diversity  of  systems  of  arrangement  in  the  min- 
eral kingdom? 

On  what  characters  did  Brewster  attempt  to  form  the  species  of  mi- 
nerals ? 

On  what  basis  have  the  writers  of  continental  Europe  founded  their  di- 
visions of  the  subject? 

from  another,  is  too  obvious  to  require  any  further  remark,  if  examples 
were  not  perpetually  presenting  themselves  of  persons  very  slenderly  pro- 
vided with  these  rudiments  of  the  science,  who  yet  undertake  geological 
investigations,  and  with  a  peremptoriness  generally  in  proportion  to  their 
ignorance,  challenge  the  credit  of  new  discoveries,  or  call  in  question  the 
observations  of  their  predecessors.  It  is,  indeed,  very  true  that  geological 
speculations  are  as  facinating  to  the  student  as  the  discrimination  of 
species  is  generally  repulsive ;  yet  it  ought  to  be  borne  in  mind  that  as  all 
sound  scholarship  is  founded  upon  grammar,  so  all  sound  geology  depends 
primarily  on  a  familiar  acquaintance  with  the  distinctive  characters  of 
simple  minerals." — Encyclop.  MetropoL  Mixed  and  Applied  Sciences,  vol. 
iv.,  Mineralogy,  p.  465. 

*  Whewell  on  the  Recent  Progress  and  Present  State  of  Mineralogy,  in 
Report  of  British  Association  for  1832,  pp.  324,  325. 


238  MINERALOGY. 

view  of  physical  and  chemical  characters.  .The  number,  variety, 
and  discrepancies  of  the  systems  of  mineralogy,  which  have  been 
recently  proposed,  abundantly  evince  tbe  difficulties  that  attend  the 
subject :  and  though  we  should  not  be  inclined  to  admit  thai  all 
methods  are  alike  in  point  of  value,  yet,  it  must  at  least  be  ac- 
knowledged, that  various  modes  of  arrangement  might  be  pointed 
out,  the  advantages  and  disadvantages  of  which  would  so  nearly 
correspond,  that  it  would  be  difficult,  if  not  impossible,  to  decide 
which  had  the  superiority. 

7.  But  whatever  kind  of  arrangement  might  be  adopted,  atten- 
tion must  necessarily  be   paid  both  to   physical    and   chemical 
characters,  in  arranging  and  describing  the  different  genera  and 
species  into  which  mineral  bodies  may  be  distributed.    Crystallo- 
graphical  properties  are  among  those  characteristics  of  minerals 
which  are  of  the  highest  importance ;  for  though   some  bodies 
belonging  to  the  mineral  kingdom  exhibit  no  traces  of  crystal- 
lization,   yet   they   are   comparatively  few   and   inconsiderable; 
hence  the  study  of  crystallography  is  necessarily  connected  with 
that  of  mineralogy,  and  the  subject  is  in  many  respects  so  import- 
ant, as  to  render  it  deserving  of  especial  consideration  ;  therefore, 
in  addition  to  the  remarks  on  crystalline  forms  which  may  occur 
in  the  notices  of  the  several  kinds  of  minerals,  some  further  ob- 
servations on  crystallography  will  be  added  to  the  latter  part  of 
this  treatise. 

8.  The  physical  characters  of  minerals  require  a  few  prelimi- 
nary  remarks.;    Colour   is   one   of  those   properties   of  mineral 
bodies,  which/fhough  frequently  serviceable   in  distinguishing 
them  from  each  other,  is  by  no  means  constant;  for  though  there 
are  some  minerals  which  always  exhihit  the  same  tints,  there  are 
others  which  display  the  utmost  diversity ;    so  that  specimens 
having  an  apparent  identity  of  chemical  constitution,  and,  in  most 
respects,  of  physical  character,  will  yet  be  found  of  very  dif- 
ferent colours.     This  is  especially  the  case  with  those  mineral 
bodies  which  are  considered  as  precious  stones,  and  when  cut  and 
polished,  used  as  ornaments. 

9.  Thus  the  gem  called  the  sapphire,  sometimes  exhibits  its 
characteristic  sapphirine,  or  blue  colour,  and  is  likewise  found 
purple,  red,  green,  yellow,  gray,  and  white,  or  perfectly  transpa- 
rent.    Topazes  are  found  yellow,  pale  blue,  green,  transparent  or 
colourless,  and  sometimes  of  a  fine  red.     Garnets  occur  not  only 
red,  but  also  black  and  brown.     The  diamond  is  seldom  entirely 
free  from  colour,  and  some  are  found  blue,  pink,  dark  brown,  or 
yellow.     Some  minerals,  as  the  opal,  exhibit  different  colours 
when  viewed  by  transmitted  light,  from  those  which  appear  when 
seen  by  reflected  light.  "\ 

What  two  characters  of  minerals  must  necessarily  be  regarded  in  making 
systematic  arrangements  ? 

What  degree  of  constancy  is  found  in  the  colours  of  minerals? 
What  examples  of  diversity  in  colour  can  be  cited  ? 


PROPERTIES  OF  MINERALS.  239 

10.  Yet  notwithstanding  these  anomalous  phenomena,  the 
colour  may  frequently  be  employed  as  a  discriminating  charac- 
teristic of  mineral  bodies;  for  though,  when  considered  alone, 
it  might  afford  no  certain  indication  of  the  nature  of  a  mineral, 
yet,  taken  in  conjunction  with  other  characters,  it  will  be  found 
frequently  useful,  as  enabling  us  to  describe  and  distinguish 
mineral  substances. 

11. {Lustre  is  one  of  the  external  characters  of  minerals,  which 
is  of  considerable  importance.  The  principal  kinds  of  lustre  are 
the  adamantine,  the  vitreous,  the  oily,  the  resinous,  the  fatty,  the 
pearly,  and  the  metallic ;  to  which  may  be  added  the  semi-metal- 
lic. The  metallic  lustre  is  peculiar  to  certain  metallic  ores,  and  is 
always  accompanied  by  opacity  ;  and  the  semi-metallic  charac- 
terizes various  earthy  as  well  as  metalliferous  minerals. 

12.  /Mineral  substances  also  differ  in  the  degree  as  well  as  the 
kind  ol  lustre  which  they  display.     Thus  the"  highest  degree  of 
brilliancy  is  termed  splendid,  whence  we  descend  through  the  va- 
rious grades  of  shining,  glistening,  and  glimmering,  till  we  arrive 
at  that  which  is  called  dull,  to  be  observed  in  most  of  those 
minerals  the  fracture  of  which  is  earthy.    This  characteristic  may 
also  be  further  modified,  and  terms  employed  to  denote  interme- 
diate degrees  of  lustre.     Thus  it  may  be  stated  that  the  lustre  of 
a  mineral  is  strongly  or  faintly  glimmering,  passing  into  glistening, 
but  such  distinctions  are  scarcely  necessary,  except  in  describing 
newly  discovered  substances. 

13.  'VThe  different  kinds  of  lustre  undoubtedly  depend  upon 
optical  differences  in  the  surfaces,  which  differences  have  not  as 
yet  been  clearly  explained.)     Professor  Breithaupt  is  in  the  habit 
of  showing,  by  the  superposition  of  a  number  of  watch-glasses, 
that  the  pearly  lustre  results  from   the  lamellar  structure  of  a 
transparent  mass.     The  very  curious  difference  between  the  opti- 
cal properties  of  the  surfaces  of  metals,  and  of  transparent  bodies, 
has  been  traced  on  different  roads,  by  Sir  David  Brewster  and  by 
Professor  Airy,  and  both  agree  in  considering  the  optical  properties 
of  the  diamond  as  intermediate  between  the  transparent  and  the 
metallic  character,  though  they  do  not  agree  in  their  representa- 
tion of  the  peculiar  laws  which  the  diamond  discloses.  When  the 
connexion  of  these  properties  with  those  of  other  bodies  is  clearly 
made  out,  we  shall  probably  learn  more  distinctly  than  we  now 
can,  what  is  the  precise  distinction  of  metallic,  adamantine,  and 
vitreous  lustre."*1 

14\  Transparency  is  a  property  which  does  not  belong  to  all 

What  dependence  for  colour  is  found  among  minerals  on  the  direction 
of  the  light  by  which  they  are  viewed  ? 

What  classification  may  be  formed  on  the  ground  of  the  lustre  of  mine- 
ral substances? 

What  property  is  found  connected  with  metallic  lustre  ? 

flow  many  divisions  may  we  form  on  the  degree  of  brilliancy  ? 

To  what  is  the  difference  in  lustre  probably  ascribable  ? 

*  Whewell  on  Mineralogy,  in  Rep.  of  Brit.  Assoc.  for  1832,  p.  327. 


240  MINERALOGY. 

minerals,  and  in  those  which  possess  it,  it  exists  in  different  de- 
grees. ^Some  minerals  are  semi-transparent,  as  cornelian,  and 
certain  kinds  of  obsidian ;  others  are  merely  translucent,  or  but 
little  removed  from  opacity.  A  few  minerals  which  appear 
opaque,  when  examined  in  the  air,  become  more  or  less  transpa- 
rent if  immersed  in  water.  This  is  the  case  with  a  sort  of  opal, 
hence  called  hydrophane.T 

15.  Hardness  is  very  important,  because  it  is  a  very  constant  pro- 
perty in  most  simple  minerals.     Professor  Moris,  of  Vienna,  has 
formed  a  scale  of  numbers  to  indicate  the  degree  of  this  property 
respectively  belonging  to  any  mineral.   In  this  scale  the  hardness 
of  common  talc  is  1,  of  gypsum  2,  of  calcspar  3,  of  fluor  spar 
4,  of  apatite,  or  asparagus  stone  5,  of  feldspar  6,  of  quartz  7,  of 
topaz  8,  of  corundum  9,  and  of  diamond  10.  \ 

16.  The  hardness  of  a  mineral  may  be  ascertained  by  trying 
whether  it  will  scratch  another,  the  relative  hardness  of  which 
is  previously  known.     Hence,  according  to  the  preceding  scale, 
supposing  the  hardness  of  a  mineral  to  be  indicated  by  5£,  it  must 
be  inferred  that  it  is  intermediate  between  5  and  6,  and  therefore 
that  it  would  scratch  apatite,  and  be  scratched  by  feldspar.     Pro- 
fessor Breithaupt,  of  Freyberg,  has  extended  the  numerical  scale 
of  Mohs  from  10°  to  12°,  by  introducing  mica  between  gypsum 
and  calcspar,  and  sodalite  between  apatite  and  feldspar,  as  inter- 
mediate degrees;  and  it  is  obvious  that,  if  it  were  thought  desir- 
able, further  distinctions  might  be  made,  and  the  scale  might  be 
enlarged." 

17.  It  is  an  observation  of  some  importance  with  respect  to  the 
hardness  of  several  minerals,  that  it  appears  lobe  different  in  dif- 
ferent parts,  and  even  in  different  directions.   Thus  the  edges  and 
solid   angles   of  crystals   seem  to  be  harder  than    their  faces ; 
and  in  the  diamond,  serviceable  cutting  points  can  only  be  obtain- 
ed from  natural  crystals.     The  diamond-cutters  distinguish  the 
angles  of  a  dodecaedral  crystal  into  hard  arid  soft  points,  the  for- 
mer consisting  of  those  which  are  also  the  angles  of  the  primitive 
octaedron,  and  which  cannot  be  split  or  broken  off,  but  must  be 
ground  down  with  diamond  powder ;  while  the  low  triangular 
pyramids,   which   form  the  other  points,   may  be   removed  by 
cleavage.    Kyanite  affords  an  example  of  a  mineral,  the  hardness 
of  which  will  differ  according  as  it  is  scratched,  along  or  across 
the  direction  of  its  axis. 

What  effect  on  the  transparency  of  certain  minerals  is  derived  from  fill- 
ing their  pores  with  water? 

What  substances  have  been  adopted  as  standards  of  hardness  ? 

How  is  the  hardness  of  an  unknown  mineral  to  be  tested  ? 

How  is  the  hardness  of  a  mineral  found  to  vary  ? 

What  distinction  is  formed  by  diamond  cutters  in  regard  to  the  angles 
of  crystals? 

What  example  of  different  degrees  of  hardness,  depending  on  direction 
is  known  to  exist  ? 

*  From  the  Greek  "Y<Jw/>,  water,  and  <J>a«Vw,  to  shou.  light 


PROPERTIES  OF  MINERALS.  241 

18.  Consistency  is  a  property  which  is  intimately  connected  with 
hardness,  but  of  a  more  general  nature.   A  substance  may  be  at  the 
same  time  very  hard  and  very  brittle,  or  it  may  be  extremely  soft, 
and  at  the  same  time  tough  or  tenaceous.     Thus  euclase  and  an- 
thophyllite  are  hard  bodies,  but  easily  frangible,  or  broken   by  a 
blow;  while  asbestus  or  amianthus,  which   are  very  soft  and 
flexible    minerals,  are  at  the  same  time  very  tenacious,  so  that 
fibres  of  these  substances  may  be  twisted  into  threads,  and  woven 
to  make  cloth. 

19.  Density ,  or  specific  gravity,  is  one  of  the  properties  of  mineral 
bodies  deserving  of  attention,  as  furnishing  the  means  of  discrimi- 
nating them  from  each  other.   The  nature  of  this  property  of  matter 
with  regard  to  substances  in  general,  has  been  amply  noticed  in  the 
preceding  volume  of  this  work,  in  which,  likewise,  the  modes 
of  ascertaining  the  specific  gravity  of  bodies,  has  been  described 
and  illustrated.* 

20.  Much  attention  has  been  paid  to  specific  gravity,  as  a  cha- 
racteristic property  of  minerals,  by  Professors  Mohs  and  Brei- 
thaupt,  who  have  determined  most  minutely  the  value  of  this  ele- 
ment for  very  extensive  series  of  minerals.  Beudant  has  discovered 
that  large  crystals,  and  especially  bacillary  masses,  are  inferior 
in  specific  gravity  to  small  crystals  ;  and  he  therefore  recommends 
the  pulverization  of  minerals  previously  to  trials  of  their  specific 
gravity,  in  order  to  obviate  the  uncertainty  that  might  arise  from 
these  differences  in  the  mode  of  aggregation.    Magnus  found  that 
garnet  and  similar  minerals,  when  melted,  and  again  solidified  in 
a  glassy  but  uncrystalline  state,  have  their  density  diminished  by 
the  operation ;   the  Greenland  garnet,  for   instance,   when  thus 
treated,  had  its  specific  gravity  reduced  from  3.9  to  3.05.f 

21.  Taste  and  odour  wee  sensible  qualities  of  minerals,  which 
cannot  be  very  extensively  applied  to  practical  purposes.     Taste 
is  chiefly  confined  to  saline  minerals,  and  is  sufficiently  obvious  in 
most  cases  where  it  exists,  as  in  rock-salt,  (chloride  of  sodium,) 
and  alum,  (sulphate  of  alumine.)  Some  minerals  are  distinguished 
by  a  peculiarly  disagreeable  smell,  as  is  the  case  with  a  particular 
kind  of  limestone,  which   is  hence  called  swinestone,  or  fetid 
limestone. 

22.  '\glectro-magnetism,  or  electricity,  manifests  its  influence  in 
some  minerals,  by  the  production  of  a  phosphorescent  light,  when 
they  are  subjected  to  collision  or  friction ;  and  others,  by  friction  or 

How  may  minerals  be  distinguished  in  reference  to  consistency  ? 

On  what  is  the  difference  in  the  specific  gravity  of  mineral  substances 
of  the  same  species  sometimes  found  to  depend  ? 

What  classes  of  minerals  are  possessed  of  taste  ? 

How  does  the  possession  of  electrical  properties  by  a  mineral  become 
apparent  ? 


*  Scientific  Class  Book,  pt.  i.  p.  151. 

t  Whewell  on  Mineralogy,  in  Rep.  of  Brit.  Assoc.  for  1832,  p.  326. 
X 


242  MINERALOGY. 

the  application  of  heat,  may  be  made  to  attract  liorht  bodies,  in  the 
same  manner  as  excited  glass  or  sealing  wax.*  J 

23.  There  are  many  terms  denoting  properties  or  appearances 
of  mineral  bodies  which  are  of  frequent  occurrence  in  treating 
concerning  them,  and  may  therefore  be  briefly  explained.  ^Minerals 
are  said  to  be  adhesive  when  the  newly  fractured  surface  adheres  it 
applied  to  the  tongue,  as  is  the  case  with  slate.}  (Those  which 
may  be  divided   into  thin  plates  are  termed  lamellar   minerals. 

/Crystals,  the  length  of  which  greatly  exceeds  their  other  dimen- 
sions, are  called  bacillary  crystalsOand-Avhen  they  are  very  much 
attenuated,  they  are  termed  capiuary,}and'i£  they  diverge  from  a 
common  centre,  scopeform  fibres!;  .Irregular  globular  bodies  are 
styled  nodules,  or  nodular  masses,  and  those  which  have  no  sym- 
metrical form,  are  called  amorphous.^  Specular  means  smooth, 
shining,  mirror-like;  tabular,  approaching  to  flatness;  and  vesicu- 
lar, sponge-like,  or  full  of  holes  or  vesicles. 

24.  Minerals  are  properly  definite  compounds,  in  various  states 
of  complication,  of  those  elementary  bodies  with  which  chemis- 
try has  made  us  acquainted,  except  in  a  few  instances;  some 
bodies,  as  gold  and  carbon,  being  presented  to  us  by  nature  in  a 
pure  and  uncombined  form.  Among  compound  mineral  bodies  there 
are  some,  however,  which  appear  to  be  simply  aggregated,  or  to 
consist  merely  of  mingled  masses,  while  by  far  the  greater  number 
are  chemical  compounds.    When  minerals  are  simply  aggregated, 
as  for  instance,  when  gold  is  found  in  limestone,  the  separation  of 
the  metal  may  be  effected  by  the  mechanical  operations  of  pound- 
ing and  washing ;  but  in  the  case  of  chemical  compounds,  as 
sulphur  and  copper,  (copper  pyrites,)  or  oxide  of  tin,  called  wood 
tin,  the  separation  of  the  metal  from  the  sulphur  in  the  first  case, 
and   from  the  oxygen  in  the  second,  can   only  be   effected  by 
chemical  processes,  the  nature  of  which  has  been  already  de- 
scribed in  the  Treatise  on  Metallurgy. 

What  is  meant  by  the  term  adhesive  as  applied  to  minerals  ? 
What  minerals  are  called  lamellar  1 
How  are  the  terms  bacillary  and  capillary  applied  ? 
What  ones  are  called  scopeform  minerals  ? 

How  are  the  terms  nodular  and  amorphous  distinguished  from  each 
other? 

How  are  specular,  tabular,  and  vesicular  used  in  mineralogy  ? 
How  may  simple  aggregates  be  separated  ? 

*  The  effect  of  heat  and  friction  in  exciting  phosphorescence  or  electric 
li<rht,  has  been  noticed  in  the  Scientific  Class  Book,  pt.  i.  pp.  337,  338. 
The  development  of  electric  attraction  by  heat  or  friction,  has  been  ob- 
served and  made  the  subject  of  experiments  by  Haiiy,  and  other  mineralo- 
gists. The  electric  property  of  the  tourmaline  long  since  attracted  atten- 
tion, and  among  the  minerals  capable  in  some  degree  of  similar  excitation, 
may  be  mentioned  boracite,  topaz,  axinite,  mesotype,  prehnite,  calamine, 
and  sphene  or  titanite.  See  Encyclop.  Metrop.,  Mixed  Sciences,  vol.  ii 
Electricity,  pp.  131—134. 


PROPERTIES  OF  MINERALS. 


243 


25.  Among  the  ultimate  or  constituent  elements  of  minerals 
may  be  mentioned, 


Oxygen 

Hydrogen 

Chlorine 

Nitrogen 

Sulphur 

Selenium 

Carbon 

Phosphorus 

Water 

Glucine 

Yttria 


Postash 

Soda 

Lithia 

Barytes 

Strontia 

Lime 

Magnesia 

Alumine 

Zicron 

Thorina 

Ammonia 


Adds.  Metals. 

Carbonic  Acid  Platina 

Phosphoric  A.  Gold 

Fluoric  A.  Silver 

Sulphuric  A.  Mercury 

Muriatic  A.  Palladium 

Nitric  A.  Rhodium 

Boracic  A.  Iridium 

Tungstic  A.  Osmium 

Chromic  A.  Copper 

Molybdic  A.  Nickel 

Telluric  A.  Iron 

Arsenic  A.  Tin 

Titanic  A.  Zinc 

Columbic  A.  Cadmium 

Antimonic  A.  Tungsten 

Vanadic  A.  Bismuth 

Silicic  A.  Cobalt 

Succinic  A.  Manganese 

Mellitic  A.  Molybdena 

Uranium 
Cerium 
Antimony 
Chromium 
.Columbium 
Arsenic 
Titanium 
Tellurium 
Vanadium. 

What  are  among  the  non-metallic  elements  found  in  minerals  ? 
Which  of  the  acids  exist  in  the  mineral  kingdom  ? 
How  many  metals  belong  to  this  department  of  nature  ? 
Into  hoW  many  classes  did  mineralogists  formerly  divide  the  substances 
treated  of  in  this  science  ? 


244  MINERALOGY. 


Classification  of  Minerals. 

26.  The  earlier  systematic  writers  on  mineralogy  in  general 
arranged  mineral  substances  in  four  classes,  namely,  earths,  salts, 
bitumens,  and  metals ;  subdividing  these  into  orders  depending  on 
their  textures  or  other  physical  properties.     Such  systems  were 
superseded  in  Germany  by  that  of  Werner,  founded  on  the  joint 
consideration  of  chemical  and  external  characters  ;   and  the  ar- 
rangement of  that   distinguished   philosopher  was,  with    some 
modifications,  for  a  long  time  generally  adopted  by  mineralogists 
in  other  countries.  Werner  and  his  followers  employed  the  division 
of  classes  above  stated,  only  substituting  the  term  inflammables 
or  combustibles  for  that  of  bitumens ;  but  the  sections  or  subdi- 
visions were  variously  altered  and  improved./  f  n  France  a  system 
was  proposed  by  Haiiy,  founded  on  crystallization,  as  the  most 
distinguishing  character  of  minerals.     He  defined  a  mineral  spe- 
cies to  consist  of  individual  bodies  similar  in  their  composition, 
and  with  crystalline  forms  also  similar);'  Some  minerals,  however, 
are  not  crystallized,  and  such  he  distributed  according  to  their 
chemical  composition.  "The  definition  which  seems  to  be  recog- 
nized in  the  crystallometrical  school  of  more  modern  times  is,  the 
same  primary  form  with  the  same  fundamental  angles  of  cleavage, 
combined  with  an  approximate  identity  of  chemical  and  physical 
characters."*  "> 

27.  Both  the  system  of  HaUy  and  the  more  modern  doctrine  are 
founded  on  a  presumed  relation  between  chemical  composition  and 
crystalline  form,  examples  of  which  are  too  numerous  to  admit  ot 
the  least  question,  but  concerning  the  nature  and  extent  of  the 
relation  we  are  not  yet  qualified  by  any  means  to  decide ;  and 
hence  arises  a  manifest  source  of  imperfection  and  discrepancy  in 
the  mineralogical   arrangements  derived  from  it.     Observations 
that  have  been  made  of  the  analogy  of  form  between  bodies  vary- 
ing in  composition,  led  to  the  assumption  of  the  principle  of  iso- 
morphism, or  plesiomorphism ;  which,  as  being  connected  with 
crystallization,  will  be  further  noticed  in  treating  of  that  subject. 

28.  Professor  Berzelius  has  constructed  an  arrangement  of  mi- 
neral bodies,  founded  on  their  relative  electro-positive  and  electro- 
negative properties.     This  system,  since  it  was  first  proposed  in 
181G,  has  been  considerably  modified,  especially  in  consequence 
of  the  discoveries  that  have  been  made  relative  to  isomorphism  ; 
and  though  still  necessarily  imperfect,  it  may  be  regarded  as  the 

What  was  the  basis  of  Werner's  divisions  ? 
How  did  Haiiy  form  his  classes? 
How  did  he  classify  uncrystallized  substances? 

How  many  distinct  characters  are  embraced  in  the  modern  definition 
of  crystals  ? 

What  characters  has  Prof.  Berzelius  made  the  foundation  of  his  system  ? 

*  Whcwcll  on  Mineralogy,  in  Rep.  of  Brit.  Association  for  1832,  p.  350. 


ARRANGEMENT  OF  MINERALS.  245 

nearest  approximation  yet  obtained  towards  a  regular  and  consist- 
ent classification  of  mineral  substances. 

29.  "  The  order  established  by  the  electro-chemical  relation  of 
bodies  is  supposed  to  be  generally  preserved  in  all  their  combina- 
tions.    Thus,  if  A  be  electro-negative  in  respect  of  B  and  of  C,  B 
will  generally  be  electro-negative  in  relation  to  C  ;  but  this  ap- 
pears not  to  be  universally  so ;  and  sometimes  one  electro-negative 
body  is  found  combined  with  two  or  more  bases,  and  sometimes 
two  acids  are  combined  with  a  single  base.     If,  says  Berzelius, 
with  these  theoretic  notions  in  our  mind,  we  look  through  the  pro- 
ductions of  the  mineral  kingdom,  the  apparently  confused  combi- 
nations which  minerals  present  will  be  immediately  pervaded  by 
regularity  and  order.    We  perceive  an  extensive  class  of  minerals 
into  which  silex  enters  as  a  constituent,  assuming  the  character 
of  salts,  either  simple,  double,  triple,  .or  quadruple  ;  and  with 
various  excesses  of  the  acid  or  the  base.  ' 

30.  Un  the  same  manner  we  perceive  the  oxides  of  titanium,  of 
tellurium,  and  of  other  metals,  performing  the  functions  of  acids, 
and  thus  reducing  the  whole  series  of  minerals  to  one  uniform 
system  of  classification  j)  and  the  doctrine  of  definite  proportions 
introduced  within  a  few  years  into  chemistry,  might,  if  we  could 
fully  avail  ourselves  of  its  aid,  be  said  to  confer  on  this  system 
of  mineralogical  classification  a  degree  of  almost  mathematical 
precision.     But  in  consequence  of  the  difficulty  of  ascertaining 
the  proportions  of  the  actual  ingredients  of  minerals,  and  the  still 
greater  difficulty  of  distinguishing  those  which  are  essential  to  the 
species  analyzed,  we  are  not  yet  enabled  to  confer  on  a  chemical 
classification  all  the  advantages  offered  by  the  improved  doctrines 
of  chemistry."* 

31.  Professor  Whewell  has  remarked  that  though  we  do  not  at 
present  possess  any  system  of  arrangement  on  strictly  chemical 
principles,  bringing  together  in  all  cases,  the  substances  which 
most  resemble  each  other  in  external  properties,  yet  the  arrange- 
ments recently  proposed  by  Berzelius  and  others,  may  be  regarded 
as  approaching  to  such  a  perfect  system,  whether  they  be  founded 
upon  external  characters  or  on  chemical  principles.     "  The  new 
system  of  Berzelius,  or  that  of  Beudant,  or  indeed  any  of  the 
new  chemical  systems,  would  produce  a  grouping  of  substances 
which  would  at  once  be  recognised  as  far  more  natural  than  that 
of  Haiiy  or  Phillips.     The  last  system  of  Berzelius  has  been 
adopted  in  the  arrangement,  of  the  minerals  of  the  British  Museum." 

32.  The  ensuing  descriptive  notices  of  the  principal  minerals  is 
arranged  on  the  electro-chemical  classification  or  system  of  Ber- 
zelius. 

What  character  have  the  mineral  substances  into  which  silex  enters  as 
a  constituent  principle  ? 

What  function  do  the  oxides  of  titanium  and  tellurium  perform? 

*  Encycl.  Metrop. — Mixed  Sciences,  vol.  iv.,  Mineralogy,  p.  468. 
x2 


246  MINERALOGY. 


(I-) 

(2.) 


Table  of  Mineral  Classes. 

Electro-positive  metals  and  their  alloys. 
Electro-negative  bodies  and  their  combinations. 
Carbon  and  carburets. 
Selenion  and  seleniurets. 
Sulphur  and  sulphurets. 
(3.)  Oxides  of  electro-positive  metals. 

(4.)  Oxides  of  electro-negative  bodies  and  their  combinations. 
Alumina  and  aluminates. 
Silicic  acid  and  silicates. 

a.  Silicates  with  simple  bases. 

b.  Silicates  with  compound  bases. 
Titanic  acid  and  titanates. 

Colurnbic  acid  and  columbates. 
Antinionic  acid  and  antimoniates. 
Scheelic  acid  and  scheelates,  or  tungstates. 
Molybdic  acid  and  molybdates. 
Chromic  acid  and  chromates. 
Vanadic  acid  and  vanadiates. 
Boracic  acid  and  borates. 
Carbonic  acid  and  carbonates. 
Arsenius  acid  and  arseniates. 
Phosphoric  acid  and  phosphates. 
Nitric  acid  and  nitrates. 
Sulphuric  acid  and  sulphates. 
(5.)  Fluorides  and  fluates. 
(6.)  Chlorides. 

(7.)  Organico-chemical  bodies,  or  minerals  derived  from  or- 
ganized matter. 

Salts. 

Resins. 

Bitumens 

Coals. 

(1.)  Electro-positive  Native  Metals. 

32.  Iron,  though  one  of  the  most  common  of  the  metallic  bodies, 
is  not  often  found  in  the  native  state^in  consequence  of  the  power- 
ful tendency  which  it  possesses  to  combine  with  oxygen,  sulphur, 
and  other  substances.!  (  Most  of  the  existing  specimens  of  native 
iron  are  supposed  to  liave  derived  their  origin  from  meteoric 
stones ;  though  this  metal  is  said  to  have  occurred  in  the  state  of 

What  is  the  first  class  of  mineral  substances  according  to  Berzelius  ? 

What  is  the  second  ? 

How  many  subdivisions  are  comprehended  under  the  second  class? 

What  is  the  third  class  ?     What  the  fourth  ? 

What  subdivisions  belong  to  this  class? 

What  is  the  fifth  class  ?     What  is  the  sixth  ? 

How  many  subdivisions  are  found  under  the  seventh  ? 

Why  is  not  iron  found  pure  in  its  native  state  ? 


ELECTRO-POSITIVE  METALS.  247 

pure  iron  ore,  massive,  and  in  leaves  of  a  gray  colour,  having  a 
fracture  like  that  of  steel,  and  some  degree  of  malleability.  Some 
notice  of  meteoric  stones  will  be  found  in  another  part  of  this 
volume ;  but  besides  those  masses  of  ferruginous  matter,  un- 
doubtedly of  aerial  origin,  large  blocks  of  iron,  in  which  the  metal 
exists  in  various  degrees  of  purity,  have  been  discovered  in  dif- 
ferent parts  of  the  world. 

34.  Among  these  blocks  of  iron  may  be  mentioned  one  found 
at  Ellenbogen,  in  Bohemia;  the  large  mass  discovered  by  Profes- 
sor Pallas,  on  the  top  of  a  hill,  between  Abakansk  and  Belskoi 
Ostrog,  on  the  the  banks  of  the  Jenesei,  in  Siberia,  which  ori- 
ginally weighed  about  1680  pounds;  a  mass  found  in  Southern 
Africa,  and  now  in  the  cabinet  of  Haarlem,  in  Holland,  weighing 
about  250  pounds  ;  an  immense  mass  of  native  iron  from  Otumpa, 
in  the  Gran  Chaco  Gualamba,  in  South  America,  described  by 
Don  Rubin  de  Celis,  who  estimated  its  weight  at  fifteen  tons  ;  a 
mass  of  iron  from  Atacama,  resembling  the  Siberian  iron  ;  a  large 
mass  of  iron  preserved  at  Aix-la-Chapelle ;  two  large  blocks  on  a 
hill  in  the  country  of  the  Esquimaux,  near  Davis's  Straits,  pieces 
of  which  the  people  use  for  making  the  rude  blades  of  their  knives 
and  harpoons ;  a  mass  of  iron  weighing  103  pounds,  found  in 
September,  1829,  near  the  castle  of  Bohumiltitz,  in  the  circle  of 
Prachin,  in  Bohemia;  and  one  found  recently  at  Magdeburg. 
Meteoric  stones,  fell  at  Weston,  Connecticut,  in  1807,  at  Long 
Branch,  N.  J.,  Aug.  15,  1829,  and  at  Munro,  Geo.,  May  8,  1829; 
of  these,  specimens  are  preserved  in  the  collection  of  the  Academy 
of  Natural  Sciences  of  Philadelphia.  Such  of  these  masses  as  have 
been  analyzed,  have  in  general  been  found  to  consist  principally 
of  iron  alloyed  with  nickel,  but  the  Magdeburg  block,  according 
to  the  analysis  of  Professor  Stromeyer,  contains,  besides  iron  and 
nickel,  cobalt,  copper,  molybdena,  and  arsenic ;  and  the  Bohu- 
miltitz mass  appears  to  contain,  with  iron  and  nickel,  small 
quantities  of  plumbago  and  sulphur.  Native  iron,  not  meteoric, 
is  said  to  have  been  found  about  1823,  in  the  town  of  Canaan,  in 
the  state  of  Connecticut,  forming  a  thin  stratum,  or  vein,  in  a  mass 
of  mica-slate.  It  was  uncombined  with  nickel,  and  quite  malleable. 

35.  Native  copper  is  usually 
found  unalloyed,  except  with 
small  portions  of  iron  and  gold*  - 
jt  exhibits  a  great  variety  of 
beautiful  forms,  besides  those 
of  common  crystals.  Native 
copper  appears  of  a  brighter  or 
darker  colour,  as  it  is  more  or 
less  tarnished,  and  occurs  some- 
times in  considerable  masses, 

What  opinion  has  been  advanced  respecting  the  origin  of  masses  of  na- 
tive iron  found  on  the  surface  of  the  ground  ? 
Enumerate  the  localities  of  some  of  those  masses. 
What  other  ingredients  besides  iron  are  found  in  some  of  them? 


248  MINERALOGY. 

one  of  which,  found  by  Mr.  Hearne,  in  the  country  round  Hudson's 
Bay,  is  described  by  that  gentleman  in  his  journal.  Large  masses 
of  native  copper  also  occur  on  the  shores  of  Lake  Superior.  Some 
specimens  are  foliated,  some  branching,  others  in  the  forms  of 
octaedral, cubic,  prismatic,  or  other  crystals;  and  this  metal  some 
times  displays  arborescent,  and  sometimes  fibrous  or  filiform  figures, 
as  represented  in  the  margin. 

3G.  Bismuth  is  found  native,  massive,  disseminated,  and  arbores 
cent,  imbedded  in  jasper  or  other  minerals.;  (When  in  the  massive 
state  its  fresh  fracture  usually  presents  changeable  colours  like 
some  silks,  or  the  plumage  of  a  pigeon's  neck.)  Jt  is  occasionally 
found  crystallized  in  octaedrous,  or  long,  double,  triedral  pyramids, 
and  tabulated  ;  often  striated.  Native  bismuth,  disseminated  as 
quartz,  is  found  at  Lane's  mine,  in  the  state  of  Connecticut. 

37.  The  existence  of  lead  in  the  native  state  is  somewhat  pro- 
blematical.     Mr.  Rathkie  is  said  to  have  discovered  it  in  the 
island  of  Madeira,  but  the  lead  there  found  is  supposed  to  have 
been  of  volcanic  origin;  and  the  occurrence  of  native  lead  in  lava 
has  been  observed  elsewhere. 

38.  Silver  is  found  more  frequently  pure,  or  in  the  state  of 
alloy,  than  most  other  metals ;  but  it  is  most  plentiful  in  the  state 
of  native  silver. }   The  metal  is  occasionally  found  in  immense 
masses  ;  the  silver-mines  of  Kongsberg,  Norway,  formerly  afforded 
specimens,  weighing  from  100  to  150  pounds;  and  in  the  mine 

called  Nye  Forhaabning,  one  was  raised  560 
pounds  in  weight,  which  is  still  preserved  in  the 
royal  cabinet  at  Copenhagen.  Specimens  of 
native  silver  exhibit  a  diversity  of  beautiful 
forms,  such  as  arborescent,  branching,  foliated, 
and  moss-like,  or  in  delicate  curls  like  cotton 
threads.  It  is  also  found  tooth-shaped,  wire- 
shaped,  and  sometimes  canaliculate  and  serrated. 
,,  It  likewise  occurs  imbedded  in  calcareous  spar, 
|,  in  prisms  crossing  each  other  in  all  direc- 
tions. 

39.  Mercury  sometimes  occurs  native  in  globules,  disseminated  in 
coarse  sandstone,  and  other  substances.  Crystallized  cinnabar,  or 
snlphuret  of  mercury,  is  found  occasionally  sprinkled  with  globules 
of  metallic  mercury.     Native  amalgams  of  the  metal  with  silver 
occur  both  in  the  semifluid  and  solid  states.     The  hydrarguret  of 
silver  crystallizes  in  perfect  and  modified  rhombic  dodecaedrous 

In  what  state  is  native  copper  generally  found  ? 

In  what  condition  is  native  bismuth  found  ? 

What  peculiarity  does  its  colour  present? 

In  what  forms  does  it  crystallize  ? 

In  what  localities  has  native  lead  been  discovered  ? 

In  what  condition  is  silver  met  with  in  nature? 

What  remarkable  specimens  of  this  metal  have  been  obtained  ? 

What  variety  of  form  does  it  present  ? 


ELECTRO-NEGATIVE  SUBSTANCES.  249 

and  other  figures.  The  plastic  nature,  of  this  amalgam  is  taken 
advantage  of  by  the  Mexican  miners  to  mould  figures  and  ornaments 
of  this  substance. 

40.  Gold  is  found  either  in  a  state  of  purity,  or  alloyed  with  a 
few  other  metals,  and  generally  in  the  latter  state,     ft  occurs  in 
foliations  upon  quartz,  associated  with  other  substances  ;  but  the 
great  bulk  of  this  precious  metal  in  circulation,  is  principally  pro- 
cured from  alluvial  strata,  where  it  is  met  with  in  masses  of 

various  sizes.  Pure  gold  occurs  either  mas- 
sive, in  detached  crystals,  as  grains  in  the 
state  of  gold  dust,  or  interspersed  in  brown 
ironstone,  in  quartz  with  needle  ore,  in  den- 
dritic or  arborescent  crystals,  and  in  moss- 
like  masses,  consisting  of  delicate  inter- 
woven fibres,  as  in  the  marginal  figure.  In 
all  these  states  it  is  found  in  the  gold 
regions  of  Virginia,  North  and  South  Caro- 
lina, and  Georgia.  The  alloys  of  gold  are 
found  crystallized  in  minute  cubes  and  octaedrons,  variously  ag- 
gregated in  reticular  plates  and  other  forms. 

Auriferous  silver,  or  electrum,  is  an   alloy  of  a  yellowish-white 
colour,  containing  gold  in  various  proportions. 

41.  P latino,  occurs  in  small  grains,  very  heavy,  and  of  a  silvery- 
white  lustre.  These  grains  are  found  in  the  alluvial  strata.    With 
platina  are  intermixed  other  metallic  bodies,  as  the  alloy  of  iridium 
and  osmium,  in  shining  foliated  grains.     Palladium  is  found  in 
delicate   scaly   grains,    of  a  lead   colour,  alloyed  with   platina. 
Rhodium  is  a  white  metal,  which,  with  platina,  iridium,  iron,  &c., 
forms  a  black  alloy. 

Electro-Negative  Metallic  and  Metalloidal  Substances,  and  their 
Non-Oxidized  Combinations. 

Tellurium  and  Tellurets. 

42.  Native  tellurium  is  a  mineral  gene- 
rally of  a  white  colour,  with  a  metallic  lus- 
tre,which  occurs  massive,  fine-grained,  and 
disseminated,  in  the  mines  of  Transylvania. 
Graphic  tellurium  occurs  of  a  grayish 
colour,  with  a  metallic  lustre,  sometimes 
tarnished,  exhibiting  delicate  tetraedral 
and  hexaedral  prisms,  aggregated  or  in- 
terwoven on  the  surfaces  of  other  minerals, 
so  as  to  have  some  resemblance  to  Arabic 

What  is  the  most  common  state  of  native  gold  ? 

With  what  rock  is  it  chiefly  associated  ? 

In  what  soil  are  the  grains  and  fragments  of  gold  usually  met  with? 

How  do  its  alloys  commonly  present  themselves  ? 

In  what  state  does  platina  occur  ? 

In  what  situation  is  it  found  ?    What  metals  usually  accompany  it  ? 

Tinder  what  different  appearances  does  native  tellurium  occur  ? 


250  MINERALOGY. 

or  Hebrew  characters.   This  mineral  contains  a  portion  of  gold,  as 
also  does  the  yellow  tellurium.     Black  tellurium  contains  lead. 

43.  Native  antimony  is  found  in  the  mines  of  Dauphine.    It  has 
a  white  colour  like  tin,  and  a  granular  and  foliated  fracture :  it 
occurs  massive,  rarely  distinctly  crystallized.    Antimonial  silver, 
or  stibiuret  of  silver,  is  found  in  the  Hartz  mountains,  of  a  bright 
white  colour,  massive,  and  crystallized  in  cubes  or  striated.  Anti- 
mony is  also  found  alloyed  with  other  metals,  as  nickel  and  lead. 

Jlrsenic  and  Jlrsneiurets. 

44.  Native  arsenic  has  nearly  the  colour  of  tin,  but  soon  becomes 
tarnished.    It  exhibits  reniform  and  botryoidal  figures.   Arseniuret 
of  nickel,  commonly  called  kupfer-nickel,  or  copper  nickel,  has 
the  colour  of  tarnished  copper.     Arseniuret  of  cobalt  comprises 
the  mineral  called  gray  cobalt,  from  its  steel-gray  colour.     Arse- 
niuret of  bismuth  is  found  in  small  brownish  globules  at  Schnee- 
berg,  in  Saxony. 

Carbon  and  Carburets. 

65.  This  is  a  mineral  which  exhibits  a  great  dissimilarity  of 
form  and  appearance  in  different  states  or  modes  of  aggregation. 
Scarcely  any  substances  can  be  more  unlike  in  their  external  cha- 
racters than  the  diamond  and  charcoal,  though  chemical  analysis 
seems  to  demonstrate  a  perfect  analogy  of  composition.  Among 
the  minerals  which  are  considered  as  varieties  of  pure  carbon  are 
diamond,  anthracite,  and  graphite,  or  plumbago. 

46.  The  diamond  exhibits  several  crystalline  forms,  as  the 
primitive  regular  octaedron;  the  same  with  solid  angles  truncated ; 
with  edges  truncated,  forming  the  passage  into  the  rhombic  dode- 
caedron;  varieties  of  the  latter,  giving  rise  to  the  hexaedral,  pris- 
matic and  tetraedral  forms ;  cubes  with  truncated  and  bevelled 
edges;  and  hemitropic  crystals  or  macles.  This  gem  exhibits 
various  colours ;  some  having  a  brownish  or  greenish  tint,  others 
are  yellow,  and  there  are  blue,  pink,  rose-red,  and  dark  brown 
diamonds  ;  but  the  latter  are  very  rare.  Diamonds  of  a  large  size 
are  of  very  unusual  occurrence.  Among  the  most  remarkable  may 
be  mentioned  the  large  diamond  in  the  imperial  sceptre  of  Russia, 
which  was  purchased  by  Catharine  II.  for  the  sum  of  90,000/. 
paid  down,  and  an  annuity  of  4,000/.  to  the  seller ;  its  weight 
is  193  carats,  and  its  size  nearly  that  of  a  pigeon's  egg.  This 
gem  is  considerably  exceeded  in  weight  and  dimensions  by  one 
which  belongs  to  the  Rajah  of  Mattan,  in  the  island  of  Borneo, 
where  it  was  found  about  a  hundred  years  ago.  In  shape  it  re- 
sembles an  egg,  with  an  indentation  near  the  smaller  end.  It  is 
said  to  be  a  stone  of  the  finest  water :  its  weight  is  367  carats,  or 

In  what  localities  is  antimony  obtained  ? 

What  is  the  colour  of  native  arsenic  ? 

In  what  forms  does  carbon  occur  in  nature  ? 

What  variety  of  external  characters  is  found  in  the  diamond  ? 

What  remarkable  specimens  of  this  mineral  have  been  found  ? 


SELENION  AND  SELENIURETS. 


251 


2  ounces,  169.87  grains  Troy.  A  Dutch  governor  of  Batavia, 
wishing  to  purchase  this  diamond,  offered  to  the  rajah,  in  exchange, 
150,000  dollars,  two  large  brigs  of  war,  with  their  guns  and  am- 
munition, together  with  other  pieces  of  cannon,  and  a  quantity  of 
powder  and  shot;  but  the  rajah  refused  to  part  with  the  gem,  to 
which  the  Malays  attributed  the  power  of  curing  diseases,  and  the 
possession  of  other  miraculous  properties. 

47.  Anthracite,  or  kohlenblende,  is  a  carbonaceous  mineral,  one 
variety  of  which  is  called  Kilkenny  coal.  Anthracite  has  a  semi- 
metallic  lustre,  and  a  conchoidal  fracture,  and  is  sometimes  slaty, 
and  occasionally  columnar.  It  burns  like  charcoal,  without  flame 
or  smoke ;  whence  in  Scotland  it  is  called  blind  coal.  In  Penn- 
sylvania this  mineral  exists  in  a  great  variety  of  degrees  of  purity, 
from  that  which  has  98  per  cent,  of  carbon  to  that  which  passes 
almost  entirely  into  a  slaty  consistency ;  and  from  the  massive, 
lustrous,  compact,  jet  black  anthracite  to  the  almost  perfect  bitu- 
minous coal,  or  the  imperfectly  converted  lignite.  It  is  equally 
interesting  as  a  mineral  deposite  and  as  an  article  of  commerce, 
being,  when  pure,  unsurpassed  as  an  article  of  fuel  whether  for 
domestic  or  manufacturing  purposes. 

Graphite,  or  plumbago,  is  the  well-known  substance  commonly 
called  black-lead.  It  is  found  in  England,  Scotland,  France, 
Spain,  Germany,  the  United  States,  and  other  countries ;  but  that 
variety  which  is  most  useful  for  making  black-lead  pencils,  is 
procured  from  a  mine  at  Borrowdale,  in  England.  It  is  said  to 
occur  in  large,  roundish  masses,  imbedded  in  a  mountain  of  argil- 
laceous schistus,  traversed  by  veins  of  quartz. 

Selenion  and  Seleniurets. 

49.  Selinion  appears  to  be  a  substance  but  sparingly  distributed 
in  the  mineral  kingdom.  Among  its  compounds  may  be  noticed 
the  mineral  called  eukairite,  a  seleniuret  of  silver  and  copper  ,•  the 
seleniurets  of  lead  and  copper,  which  are  the  products  of  Swedish 
mines  ;  and  the  combination  of  selenion  with  sulphur,  occurring  in 
the  volcanic  regions  of  Italy. 

50.  The  eukairite  is  exhibited  in  the 
annexed  figure. 

Besides  these  may  be  mentioned,  the 
seleniuret  of  bismuth  and  tellurium,  that 
of  lead  and  cobalt,  the  cupriferous  sele- 
niuret of  lead,  the  seleniuret  of  lead  and 
/  mercury,  and   the  .riolite  and    culebrite, 
which  are  seleniurets  of  zinc  with  sul- 
^  phur  and  mercury. 

What  value  has  been  attached  to  these  specimens  ? 
What  are  the  characteristics  of  anthracite  ? 
What  is  the  common  name  givm  to  plumbago  ? 
What  is  the  chemical  composition  of  eukairile  ? 
What  seleniurets  occur  in  nature  ? 


252 


MINERALOGY. 


Sulphur  and  Sulphurets. 
a.  Single  Sulphurets. 

51.  Native  sulphur  occurs  in  beds  of  gypsum  or  selenite,  sul- 
phate of  strontian,  and  also,  though  more  rarely,  in  the  veins  of 
primitive  rocks.     It  is  found  in  the  mountains  of  South  America, 
in  the  Apennines  of  Piedmont,  in  the  glaciers  of  Mont  Blanc,  in 
Spain,  Hungary,  Poland,  and  Siberia.     Sulphur  occurs  crystal- 
lized, massive,  and  stalactitic.     It  appears  in  some  warm  springs 
in  such  quantities  as  to  form  a  deposit  when  the  water  is  cooled 

in  contact  with  air.  This  mine- 
ral is  often  found  sublimed,  near 
the  craters  of  volcanoes,  as  in 
Italy,  Sicily,  and  South  America. 
Sulphur  crystallizes  in  acute  oc- 
taedrons,  the  common  base  of  the 
two  pyramids  being  a  rhomboid  : 
also  spongeous  and  granular,  and 
sometimes  forming  tufted  or 
branching  crystals.  (See  mar- 
ginal fig.) 

52.  The  metallic  Sulphurets  are  numerous,  constituting  a  large 
proportion  of  the  ores  from  which  metals  are  obtained  for  economi- 
cal purposes. 

Sulphuret  of  manganese,  or  manganese  blende,  is  found  at  Nao-- 
yag,  in  Transylvania,  in  the  mines  of  Cornwall,  and  in  Peru. 

Sulphuret  of  zinc,  or  blende,  is  usually  called  by  the  English 
miners  black  Jack.  The  colour  of  this  mineral  varies  ;  some 
specimens  being  yellow,  some  brown,  and  others  black.  The  first 
is  generally  the  most  pure,  the  others  containing  iron,  silica  arid 
water,  as  well  as  zinc  and  sulphur.  One  variety  of  blende  when 
scratched  gives  out  a  phosphoric  light.  The  fibrous  blende  of 
Przbram,  in  Bohemia,  contains  cad- 
mium ;  and  the  testaceous  or  schaalen 
blende,  which  has  been  found  at  Gerold- 
seck,  in  the  Brisgau,  is  a  Sulphuret  of 
zinc  with  iron  and  a  portion  of  lead. 
This  mineral  occurs  massive,  and  in 
various  forms,  as  octaedrons,  tetraedrons, 
and  dodecaedrons,  the  primitive  crystal 
being  a  rhomboidal  dodecaedron.  Some 
specimens  exhibit  spicular  crystals,  as 
in  the  marginal  figure.  The  black  blende  is  found  at  Westches- 
ter,  Pennsylvania. 

In  what  situations  is  native  sulphur  found  ? 

In  what  forms  do  its  native  masses  present  themselves  ? 

What  are  the  figures  of  its  crystals  ? 

What  name  is  given  in  England  to  the  sulphuret  of  zinc  ? 

With  what  other  metal  is  this  sometimes  combined  ? 


SULPHURET  OF  COPPER. 


253 


53.  Sulphuret  of  iron,  or  pyrites,  is  among  the  most  abundant 
mineral  products  in  various  parts  of  the  world.     Large  crystals 
of  this  substance  have  been  met  with  in  the  sepulchres  of  the 

Incas  of  Peru,  and  they 
are  supposed  to  have  been 
used  as  mirrors.  No- 
dules or  globular  masses 
are  sometimes  found  in 
chalk.  Its  primitive  form 
is  the  cube ;  but  it  oc- 
curs variously  crystal- 
lized, as  in  the  annexed 
figure. 

54.  Radiated  pyrites  (a  variety  frequently  including  the  lenti- 

cular or  coxcomb,  and  the  globular  pyrites) 
is  very  liable  to  spontaneous  decomposi- 
tion and  inflammation,  sometimes  pro- 
ducing mischievous  consequences  in  mi- 
neralogical  cabinets.  Magnetic  pyrites 
occurs  massive,  foliated,  and  crystallized 
in  hexaedral  prisms.  Pyrites  exhibits  a 
metallic  appearance,  much  resembling 
brass  or  pinchbeck. 

55.  Sulphuret  of  cobalt  is  seldom  found  crystallized,  occurring 
massive  and  disseminated.     Its  colour  is  pale  *eel-gray ;  when 
tarnished,  reddish  ;    and  it  yields  a   sulphureous  vapour  when 
heated.    The  mines  of  Tunaberg  and  Bastnaes,  in  Sweden,  afford 
cobalt  pyrites. 

56.  Sulphuret  of  nickel,  formerly  supposed  to  be  native  nickel, 
till  its  composition  was  ascertained  by  Arfvedson,  occurs  in  the 
capillary  form,  or  that  of  long,  wire-shaped  crystals,  of  a  brass- 
yeliow  tint,  tarnished. 

57.  Sulphuret  of  copper  is  the 
most  common  ore  of  that  metal, 
including  some  varieties.  It  is  found 
in  several  forms  as  compact,  foliated 
or  crystallized,  the  primitive  form 
being  an  acute  octaedron,  with  a 
square  base.  (See  marginal  figure.) 
One  variety  is  the  malleable  copper 
ore,  peculiar  to  Siberia  :  the  colour 
said  to  be  a  shining  steel-gray. 

What  is  the  primitive  form  of  the  sulphuret  of  iron  ? 

For  what  purpose  does  the  lustre  of  this  substance  allow  it  to  be  used  ? 

What  occurs  when  radiated  pyrites  is  exposed  to  the  air? 

How  do  we  find  sulphuret  of  cobalt  ? 

What  is  the  appearance  of  sulphuret  of  nickel? 

In  what  combination  does  copper  most  frequently  present  itself? 


254  MINERALOGY. 

The  sulphurets,  called  yellow  copper  and  copper  pyrites,  contain 
much  iron,  as  well  as  copper  and  sulphur.  Variegated  or  peacock 
copper  ore,  which  is  of  this  kind,  exhibits  fine  iridescent  colours. 
Among  the  sulphurets  of  copper  may  be  reckoned  the  secondary 
fossils,  styled  Frankenberg  corn-ears,  which  are  found  in  bitumi- 
nous marl-slate,  at  Frankenberg,  in  Hesse ;  and  are  chiefly  com- 
posed of  vitreous  and  gray  copper.  Tennantite,  found  in  copper 
mines  near  Redruth,  in  Cornwall,  appears  to  differ  from  gray 
copper  ore,  in  containing  more  sulphur  and  less  iron,  and  in  pos- 
sessing greater  hardness. 

58.  Sulphuret  of  lead,  or  galena,  is  the   most  important,    as 
well  as  the  most  common  of  the  ores  of  this  metal,  constituting 
the  principal  source  from  which  it  is  obtained.    It  usually  contains 
silver,  in  addition  to  lead  and  sulphur.     It  occurs  in  extensive 
beds  and  veins,  in  primitive  and  secondary  rocks,  most  abundantly 
in  argillaceous  schist  and  secondary  limestone ;  and  it  is  acom- 
panied  by  the  ores  of  zinc,  copper,  iron  and  silver ;  and  by  quartz, 
sulphate  of  barytes,  carbonate  of  lime,  and  fluoride  of  calcium, 
(fluorspar.)  Much  of  this  ore  is  obtained  from  the  mines  of  Missouri, 
where  it  is  found  massive,  or  crystallized  in  cubes  and    regu- 
lar octaedrons,  sometimes  of  gigantic  size.    The  peacock  lead  ere 
of  the  miners  displays  various  purple  tints,  like  a  dove's  or  pea- 
cock's neck.     A  compact  and  specular 
variety  is   styled   by   the    Derbyshire 
miners  "  slickenside."     Blue  lead  ore, 
crystallized    in   hexagonal    prisms,   is 
found  at  Huelgoit,  in  Bretagne.     Anti- 
moniated  galena,  of  a  tin-white  colour, 
aggregated  crystals,  contains,  besides 
lead  and  sulphur,  a  large  portion  of  an- 
timony. 

59.  Sulphuret  of  bismuth,  or  bismuth  glance,  occurs  massive,  or 
in  delicate  acicular  crystals.  Cupreous  bismuth  ore  is  a  sulphuret 
of  bismuth  and  copper,  which  is  found   massive   and  dissemi 
nated.     Needle  ore,  a  sulphuret  of  bismuth,  lead  and    copper, 
which    derives   its   appellation  from   its    wire-like   appearance, 
occurs  imbedded  in  quartz. 

60.  Sulphuret  of  tin,  or  tin  pyrites,  also  called  bell-metal  ore, 
from  its  colour,  is  a  compound  of  sulphur,  tin,  and  copper,  with 
a  small  portion  of  iron. 

61.  Sulphuret  of  mercury  exhibits  some  diversity  of  colour  and 
form.  There  are  two  varieties,  sinnabar,  and  hepatic  mercurial  ore, 
the  former  of  which  is  divided  by  Werner  into  the  dark  red  cin- 
nabar, the  colour  of  which  approaches  that  of  cochineal ;  and  the 

What  other  metal  is  sometimes  mixed  with  the  sulphuret  of  copper? 

What  is  the  common  name  of  the  sulphuret  of  lead  ? 

In  what  kind  of  rock  is  it  generally  found  ? 

What  is  meant  by  cupreous  bismuth  ?    What  by  needle  ore  ? 

What  is  the  true  composition  of  tin  pyrites  ? 

What  name  is  commonly  given  to  the  sulphuret  of  mercury  ? 


COMPOSITE  STJLPHURETS.  255 

bright  red  or  native  vermilion.  The  hepatic  mercurial  ore,  or 
liver  ore  is  a  mixture  of  cinnabar  with  bituminous  and  earthy 
matter  compact  and  slaty,  found  in  the 
m'nes  °f  Idria.  Coral  ore  is  of  the  same 
nature,  with  petrifactions.  This  sulphuret 
occurs  disseminated  and  superficial,  form- 
*n£  aroorescent  figures  on  clay-slate,  &c. 
(See  marginal  figure.) 

62.  Sulphuret  of  silver,  or  vitreous  sil- 
ver ore,  occurs  massive,  or  crystallized  in 
cubes,  octaedrons,  and  dodecaedrons,  besides  other  forms.  Black 
silver  ore  is  a  pulverulent  variety  of  this  sulphuret,  having  a 
scoriaceous,  sooty  appearance  ;  sometimes  massive,  or  coating 
native  silver. 

63.  Sulphuret  of  antimony,  occurs  compact,  foliated,  radiated, 
or  plumose;  composed  of  downy  fibres,  disposed  in  nests,  or  fas- 

cicu]ar  crystals.  (See  marginal 
figure.)  Some  varieties  exhibit 
a  fine  iridescent  blue,  yellow, 
and  red  tarnish. 

64.  Sulphuret  of  arsenic,  when 
it  contains  a  large  proportion  of 
sulphur,  constitutes  the  mineral 
called  orpiment,  characterized  by 
its  bright  yellow  colour  ;  with  a 
less  proportion  of  sulphur,  arse- 
nic forms  realgar,  or  red  orpiment. 
The  latter  is  said  to  occur  chiefly  in  primitive  rocks,  but  the  yel- 
low orpiment  in  the  secondary  or  floetz  rocks  of  Werner;  and 
both  are  found  near  volcanos.  These  minerals  are  sometimes 
massive,  or  lamellated  ;  and  occasionally,  but  more  rarely,  crystal- 
lized. 

05.  Sulphuret  of  molybdena  is  a  sectile,  shining  substance,  re- 
sembling plumbago,  and  generally  massive  or  laminated  ;  rarely 
crystallized.  It  is  found  in  Sweden,  Bohemia,  and  near  Mont 
Blanc,  disseminated  in  a  gray  granite.  It  has  also  been  met  with 
in  Cornwall,  and  in  Inverness-shire,  North  Britain. 

b.  Composite  Sulphurets. 

66.  Sulphuret  of  arsenic  and  iron,  arsenical  pyrites,  or  mispickel, 
occurs  principally  in  veins  in  primitive  mountains,  and  is  common 
in  the  copper  mines  of  Cornwall.  It  is  often  iridescent.  Some 
varieties  are  argentiferous,  and  exhibit  a  tarnished  silver  hue. 


What  is  the  true  character  of  black  silver  ore? 

What  is  the  appearance  of  sulphuret  of  antimony? 

What  is  the  chemical  character  of  orpiment  and  realgar  ? 

What  peculiar  properties  belong  to  sulphuret  of  molybdena? 

In  what  localities  has  it  been  found  ? 

To  what  triple  compound  is  the  name  arsencial  pyrites  applied  ? 


256 


MINERALOGY. 


Glance  cobalt  is  an  arsenio-sulphuret  of  co- 
balt, which  is  found  massive,  and  crystallized 
in  cubes,  octaedrons,  dodecaedrons,  and  va- 
rious other  derivative  forms. 

67.  Among  the  composite  sulphur  salts  may 
likewise  be  mentioned  the  bournonite  (so 
called  from  its  discoverer,  Count  Bournon,) 
which  is  a  sulphuret  of  lead,  antimony,  and 
copper,  crystallized  in  tetraedral  prisms,  va- 
riously modified. 

68.  Red  or  ruby  silver  ore  is  distinguished  into  two  kinds,  the 
dark  red  and  the  light  red,  both  crystallizing  in  hexaedral  prisms  ; 
but  the  former  is  a  sulphuret  of  silver  and  antimony,  and  the  latter 
a  sulphuret  of  silver  and  arsenic  :  there  are  also  other  varieties. 

Gray  copper  ore,  or  fahlerz,  is  a  double  sulphur  salt,  of  copper  and 
antimony. 

Oxides  of  the  Electro-Positive  Metals. 

69.  The  oxides  of  manganese  occur  in  considerable  variety,  and  are 
very  generally  disseminated.   Fibrous  gray  manganese  crystallizes 

in  delicate  acicular  crystals, 
and  other  varieties  are  radiat- 
ed, foliated,  or  compact,  the 
latter  sometimes  in  botryoidal 
masses.  f]arthy  gray  man- 
ganese is  much  used  in  the 
preparation  of  oxygen  gas. 
Fibrous  black  manganese  is 
found  dendritic,  on  the  sur- 
face of  stone,  or  indurated 
marl.  (See  marginal  figure.)  Wad  is  often  ochreous,  of  a  brown 
or  black  colour.  Sulphuretted  oxide  of  manganese,  which  resem- 
bles the  gray  oxide,  is  found  with  the  ores  of  tellurium,  at  Nagyag, 
in  Transylvania.  Franklinite,  is  an  oxide  of  manganese°wilh 
zinc  and  iron. 

70.  The  oxides  of  iron  are  extremely  numerous.    Specular  oxide, 
or  iron  glance,  found  in  the  Isle  of  Elba,  is  remarkable  for  its 
beautiful  iridescent  or  changeable  colours ;  and  specimens  from 
Stromboli  and  Vesuvius  occur  in  large  lamellar  crystals,  often 
imbedded  in  lava,  looking  like  polished  steel.  Iron  mica  is  found 
in  delicate,  bright,  hexaedral,  tabular  crystals,  of  an  iron-gray 
colour.     Red  iron  ore  includes  the  varieties  of  compact  red  iron- 
stone, and  red  haematite,  the  latter  in  large  masses,  uniform,  or 
mammillated.     Magnetic   ironstone,  or  oxidulated  iron,  is  very 
common,  both  massive  and  crystallized,  in  octaedrons.     Wootz, 

What  is  meant  by  glance  cobalt?  What  is  the  composition  of  bournonite  ? 

What  is  the  nature  of  ruby  silver  ore  ?  For  what  is  the  earthy  grey 
manganese  employed  ?  What  is  Franklinite  ?  For  what  is  the  iron  ore 
of  Klba  remarkable?  What  varieties  does  the  red  iron  ore  embrace? 


OXIDE  OF  URANIUM.  257 

or  Indian  steel,  is  obtained  from  an  ore  of  this  kind,  found  in  the 
East  Indies. 

71.  Hydrous   oxide   of  iron,  ^or  brown  ironstone,   occurs   in 
several  varieties,  as  the  micaceous,  called  goethite,  forming1  trans- 
parent tables,  of  a  blood  red  hue ;  that  in  fine  scales,  lining  the 

cells  or  vesicles  found  in  lava ;  in 
the  state  of  a  dark  brown  powder, 
used  by  the  Booshuanas  of  South 
Africa,  as  hair-powder ;  the  fibrous 
brown  ironstone,  or  brown  haema- 
tite, in  silky  fibres,  or  zoned,  at- 
tached to  the  roofs  or  walls  of  ca- 
verns ;  the  compact  brown  iron  ore, 
and  brown  ochre.  Argillaceous,  or 
clay  ironstone,  occurs  in  nodules, 
reniform  masses,  £bc.  (See  marginal  figure,)  and  some  specimens 
exhibit  impressions  of  ferns  and  other  vegetables. 

72.  Among  the  oxides  of  copper  is  the  native  protoxide,  or  ruby 
copper  ore,  which  occurs  massive\and  crystallized  in  octaedrons 
and  other  figures :  and  there  is  a  variety  found  in  Germany  in 
beautiful  bright  red  capillary  crystals.     The  tile  ore,  a  compact 
earthy  variety,  is  a  mixture  of  ruby  copper  and  brown  iron  ochre. 

73.  Oxide  of  lead,  or  native  minium,  supposed  to  be  produced 
from  the  decomposition  of  galena,  has  been  found  in  the  lead- 
mines  of  Yorkshire,  England,  and  on  the  continent  of  Europe. 
Yellow  oxide  has  been  obtained  from  Siberia ;  and  an  ash-gray 
variety,  coating  galena,  is  said  to  have  occurred  in  North  Wales. 
Plomboromme,  so-called  from  its  appearance,  is  a  compound  of 
lead  with  oxygen,  alumine,  and  water,  of  a  shining  yellow  colour, 
and  mammillated. 

74.  Oxide  of  bismuth,  or  bismuth  ochre,  is  a  light  yellowish-gray 
or  greenish  mineral,  earthy  and  friable,  which  is  found  in  Saxony 
and  Bohemia. 

Oxide  of  zinc,  called  red  oxide,  from  its  colour,  occurs  dissemi- 
nated in  groups,  indeterminately  crystallized,  or  of  a  lamellar 
structure,  in  iron-mines  in  New  Jersey. 

Oxides  of  cobalt. — The  black,  brown,  and  yellow  cobalt  ochres, 
appear  to  be  hydrates,  or  combinations  of  water  with  the  oxides  of 
cobalt  and  manganese,  frequently  mixed  with  oxide  of  iron, 
v  Oxide  of  uranium,  called  uran  ochre,  exhibits  various  shades  of 
yellow.  ;Pechblende  is  a  ferriferous  oxide  of  uranium,  containing 
also  lead,  copper,  arid  other  substances. 

Whence  is  Indian  steel  obtained  ? 

In  what  variety  of  forms  does  brown  ironstone  occur? 

What  is  the  appearance  of  clay  iron-stone  ? 

What  organic  substances  does  it  occasionally  contain  ? 

How  is  the  oxide  of  copper  crystallized? 

What  is  the  chemical  nature  of  minium  ?    What  is  plorabgomme? 

Wrhere  is  native  oxide  of  zinc  found  ? 

What  is  the  nature  of  cobalt  ochres? 

What  is  Jhe  nature  of  the  mineral  called  pechblende  ? 


258  MINERALOGY. 

75.  Oxide  of  tin  includes  common  tin  ore  and  wood-tin.  The 
former  occurs  massive,  variously  crystallized,  and  disseminated  in 
granite  ;  it  also  forms  delicate  capillary  crystals.  /Wood-tin  has 
been  found  only  in  Cornwall  and  in  Mexico;  its  structure,  in 
general,  is  fibrous,  having  the  appearance  of  wood,  but  extremely 
heavy.  A  variety,  called  in  Cornwall  toad's  eye  wood-tin,  ex- 
hibits globular  concretions  of  radiating  fibres,  disposed  concentri- 
cally in  brown  and  yellow  colours.  » 

Oxides  and  Oxacids  of  Electro- Negative  Substances,  with  their  Com- 
binations. 

Alumina  and  Aluminatts. 

7G.  The  oxide  of  aluminum,  which  constitutes  in  its  pure  state 
aluminous  or  argillaceous  earth,  sometimes  occurs  alone  in  a 
crystallized  form,  and  sometimes  acts  the  part  of  an  acid,  entering 
into  combination  with  the  oxides  of  other  bodies.  Among  the 
varieties  of  native  alumina,  are  the  perfect  corundum,  which  is 
found  of  different  colours.  The  blue  kind  is  the  gem  called  the 
oriental  sapphire,  the  purple  the  oriental  amethyst,  the  yellow  the 
oriental  topaz  or  chrysolite,  the  green  the  oriental  emerald,  and  the 
red  the  oriental  ruby.  The  adamantine  spar,  or  imperfect  corundum, 
and  emery,  are  also  chiefly  composed  of  alumina,  containing  only 
very  inconsiderable  portions  of  silica  and  oxide  of  iron.  Fibrolite, 
(called,  by  Lucas,  bournonite,)  according  to  an  analysis  of  Che- 
nevix,  consists  principally  of  alumina  arid  silica.  The  indianite 
of  Count  Bournon  is  a  granular  mineral  from  the  carnatic,  con- 
taining specks  of  hornblende,  and  it  is  one  of  the  matrices  of  the 
common  corundum.  Diaspore  and  gibbesite  are  hydrates  of 
alumina. 

78.  The  aluminate  of  magnesia  occurs  in  the  spinel  or  balas 
ruby,  consisting  of  red  octaedral  crystals,  and  there  is  a  blue  kind 
of  spinel  found  in  Sudermania,  in  Sweden.  Ceylonite  or  pleonaste, 
which  has  been  reckoned  a  variety  of  the  spinel,  according  to 
Ekeberg,  contains  iron  as  well  as  alumina  and  magnesia.     The 
automalite  or  gahnite,found  in  Sweden,  and  in  New  Jersey,  has  been 
termed  the  zinc  spinel,  being  a  combination  of  alumina  with  oxide 
of  zinc.  Plombgomme,  already  mentioned,  is  a  hydrous  aluminate 
of  lead. 

Silica  and  Silicates. 

79.  The  oxide  or  acid  of  silicon,  and  its  combinations  with  the 
oxides  of  other  bodies,  form  by  much  the  most  numerous  division 

What  are  the  forms  and  localities  of  wood  tin? 

What  is  the  nature  of  corundum  ? 

Into  what  precious  stones  does  alumina  enter  as  a  chief  ingredient  ? 

What  is  emery  ?    What  is  the  chemical  composition  of  spinel  ? 

What  office  does  the  alumina  perform  in  composing  this  mineral  ? 

What  is  meant  by  zinc  spinel  ? 


ROCK-CRYSTAL  AN7D  QUARTZ.  259 

of  mineral  substances.  In  previous  arrangements  the  siliceous 
minerals  have  in  general  been  considered  as  constituting  so  many 
distinct  species,  but  they  may  with  more  propriety  be  regarded  as 
merely  varieties,  whose  peculiar  external  characters  are  respec- 
tively derived  from  the  admixture  of  extraneous  substances,  or 
from  other  circumstances  connected  with  their  formation. 

80.  Rock-crystal,  which  is  composed  of 
pure  siliceous  earth,  crystallizes  in  various 
forms,  the  primitive  crystal,  which  is  of 
rare  occurrence,  being  an  obtuse  rhomboid. 
Sometimes  it  appears  in  hexaedral  pyra- 
mids, with  aeicular  diverging  fibres,  as  in 
the  marginal  figure.    Very  fine  specimens, 
and  some  of  extraordinary  size,  are  found 
in  Madagascar,  and  among  the  Alps. 

81.  Amethyst  quartz  is  tinged  with  a 
little  iron  and  manganese.     Rose   quartz 
derives  its  roseate  hue  from  manganese. 
Red  quartz,  in  small  crystals,  coloured  by 
iron,   has  obtained  the  name  of  hyacinth 

of  compostella.  Other  varieties  are  fibrous  quartz;  flexible  sand- 
stone, found  in  Brazil,  and  at  Mount  St.  Gothard,  in  Switzerland  ; 
stalagmitic  quartz,  or  quartz-sinter,  including  the  siliceous  concre- 
tions formed  by  deposition  from  the  hot  springs  of  Geyser,  in  Ice- 
land ;  pearl-sinter,  or  fiorite,  from  the  hill  of  Santa  Fiora,  in  Tus- 
cany, and  from  the  Isle  of  Ischia;  ceraunian-sinter,  or  fulgurite, 
supposed  to  have  been  formed  by  the  action  of  lightning;  iron, 
flint,  or  ferruginous  quartz,  containing  small  quantities  of  iron; 
and  hyalite,  which  contains  water  combined  with  silica.  Prase, 
or  green  quartz,  contains  actinolite. 

82.  Avanturine  is  a  beautiful  kind  of  quartz,  of  a  rich  brown 
colour,  exhibiting  interspersed  glittering  particles,  either  from  the 
presence  of  minute  scales  of  mica,  or  from  the  occurrence  of 
abundance  of  small  fissures,  which  cause  numerous  reflections  of 
the  rays  of  light;  and  the  cat's-eye,  chiefly  from  Ceylon,  displays 
an  opalescent  lustre,  owing  to  almost  invisible  fibres  of  amianthus 
imbedded  in  the  quartz.  Hornstone  is  of  two  kinds,  called  con- 
choidal  and  splintery,  from  the  mode  of  fracture ;  its  most  usual 
colours  are  reddish-white,  milk-white,  and  very  light  gray,  some- 
times stained  with  dull  yellow  ;  and  the  splintery  hornstone  occa- 
sionally is  marked  with  small  irregular  spots,  supposed  to  be 
owing  to  the  presence  of  chlorite. 


What  elementary  principles  are  the  most  abundant  in  the  mineral  king- 
dom? 

What  is  the  substance  commonly  known  as  rock  crystal  ? 
What  is  its  primitive  form? 

Enumerate  some  of  the  varieties  which  occur  in  this  substance. 
What  peculiar  appearance  is  exhibited  by  avanturine? 


260  MINERALOGY. 

83.  Common  flint  exhibits  a 
vast  variety  of  singular  forms  and 
appearances,  most  of  which  seem 
to  be  derived  from  organic  bodies. 
Calcedony  occurs  of  different 
colours,  as  pale  blue,  gray,  and 
sometimes,  but  more  rarely,  of  a 
light  green  hue  ;  it  is  crystallized 
in  obtuse  rhomboedrons ;  speci- 
mens of  botryoidal  calcedony  are  found  in  the  Ferroe  Islands;  and 
nodules  inclosing  water  (enhydrites)  in  volcanic  rocks,  at  Monte 
Berico,  near  Vicenza,  in  Italy.  Some  specimens  exhibit  curious 
dendritic  and  other  figures  on  the  surface,  of  a  red  or  black  colour; 
they  are  called  mocha  stones,  and  are  used  for  the  covers  of  snuff- 
boxes, and  for  ornamental  purposes. 

84.  Cornelian  is  distinguished  from  calcedony  merely  by  its 
colour,  being  red  or  yellow,  and  sometimes  striped.  Plasma  is  of  a 
dullish  green  colour,  often  spotted  with  white.  Heliotrope  is  a  mix- 
ture   of    calcedony  with    green  earth,    occasionally  containing 
particles  of  red  jasper  interspersed,  whence  it  is  styled  blood- 
stone ;  some  varieties  are  yellow  spotted  and  semi-transparent. 
Chrysoprase  is  a  beautiful  variety  of  calcedony,  which  owes  its 
apple-green  colour  to  oxide  of  nickel.    Pimelite  is  a  similar  green 
siliceous  earthy  mineral,  which,  according  to  Klaproth,  contains  a 
large  proportion  of  water.     Agates  are  siliceous  compounds  of  an 
analogous   nature,  displaying  variety  of  colour,   diversified  by 
curved  and  angular  lines,  forming  multitudes  of    singular  and 
beautiful  figures.     Hence  their  several  designations  of  striped, 
zoned,  fortification,  landscape,  moss,  spotted,  and  clouded  agates. 

85.  The  jaspers   form   a   multifarious   division    of   siliceous 
minerals.     The  globular  or  Egyptian  jasper,  of  various  shades  of 
red,  is  found  at  Cairo,  in  masses  supposed  to  be  formed  by  infil- 
tration ;   riband  or  striped  jasper,  generally  of  a  brownish-red, 
with  green  bands,  occurs  in  Siberia;  agate  jasper,  found  only  in 
veins  of  agate,  exhibits  a  diversity  of  colours,  red,  white,  and  yel- 
low ;  porcelain  jasper,  which  has  a  vitrified  appearance,  is  pro- 
duced by  the  operation  of  subterraneous  heat  on  clay-slate. 

86.  Opal  is  inferior  in  beauty  of  appearance  to  few  minerals, 
being  distinguished  by  a  peculiar  chatoyant  lustre  or  play  of 
colours,  arising  from  a  multiplicity  of  minute  and  otherwise  im- 
perceptible fissures  withfh  its  substance.     These  are  the  noble 
opals,  the  finest  specimens  of  which  are  found  in  Hungary.     The 
gyrasol,  or  fire-opal,  from  Mexico,  displays  usually  reddish,  yel- 
lowish, and  greenish  tints,  with  a  flame-like  iridescence,  depend- 

What  are  the  varieties  of  oalcedony  ? 

What  is  signified  by  the  term  enhydrite?    What  is  heliotrope? 

What  is  the  composition  of  agates  ? 

What  variety  of  jaspers  may  be  enumerated  ? 


SILICATES.  261 

ing  on  interior  fissures.  The  common  opal  and  the  semi-opal  are 
destitute  of  the  play  of  colours  which  characterizes  the  noble  opal. 
Hydrophane,  or  oculus  mundi,  is  white  and  opaque  when  viewed 
in  the  air,  but  is  rendered  transparent  by  immersion  in  waler. 
Wood-opal  is  found  of  various  colours,  generally  bright  yellow, 
and  its  appearance  betrays  its  nature,  as  opalized  wood.  Jaspopal 
exhibits  red,  brown,  and  yellow  colours,  and  is  sometimes  spot- 
ted. Menilite,  so  called  because  it  is  found  at  Menil-Montant,  near 
Paris,  is  nearly  allied  to  common  opal.  All  the  opals  are  regarded 
as  hydrates  of  silica. 

«  Silicates  with  a  Single  Base. 

87.  Table-spar  or  wollastonite,  found  at  Mount  Vesuvius,  Nagyag 
in  Transylvania,  and  elsewhere,  is  a  silicate  of  lime. 

The  silicates  of  magnesia  are  more  numerous,  including  steatite, 
which  is  white,  or  mottled  like  soap,  and  of  various  colours,  the 
yellowish-green  variety  being  among  the  most  remarkable;  kef- 
fekil  or  meerschaum,  of  which  pipe-bowls  are  manufactured; 
keffekillite,  found  in  the  Crimea;  lithomarge,  sometimes  of  a  red- 
dish-yellow colour,  and  sometimes  of  a  purple  hue,  but  more  fre- 
quently white. 

8S.  Silicate  of  zinc,  called  likewise  electric  or  siliceous  calamine, 
is  obtained  from  Hungary  and  Siberia. 

Silicate  of  manganese  occurs  in  varieties,  which  have  been  distin- 
guished by  different  names,  as  allagite  and  rhodonite. 

Silicate  of  cerium,  or  ceritc,  found  at  Bastnaes,  in  Sweden,  con- 
tains yttria  as  well  as  oxide  of  cerium,  and  therefore  belongs  to 
the  next  division. 

The  silicates  of  iron  include  the  hisingerite,  the  sideroschizolite, 
and  the  chlorophaeite. 

The  silicates  of  copper  are  crysocoll,  siliceous  malachite,  or 
mountain-green,  which  contains,  according  to  Klaproth,  carbonic 
acid,  as  well  as  silica,  and  water ;  and  dioptase,  or  copper  emerald, 
a  scarce  mineral  from  Siberia. 

89.  ^ilicate  of  zirconia  includes  the  common  zircon,  and  some 
hyacinths  from  Ceylon,  and  other  countries ;  besides  the  variety 
called  zirconfte,  and  the  blue  zircon  from  Mount  Vesuvius. 

Among  the  silicates  of  alumina  are  the  kyanite  or  disthene,  and 
its  varieties,  the  bucholzite,  and  the  sillimanite.  The  hydrous 
silicates  of  alumina,  or  those  containing  water,  exhibit  considera- 

To  what  is  the  play  of  colours  in  the  "noble  opal"  attributed  ? 
What  peculiarity  is  possessed  by  the  hydrophane  '. 
What  is  the  chemical  nature  of  this  class  of  minerals? 
What  is  meant  by  the  term  silicate  1  (See  Chemistry  No.  309.) 
What  use  is  made  of  the  silicate  of  magnesia  called  keffekil  I 
Where  is  silicate  of  zinc  found  ? 
What  different  varieties  of  silicate  of  copper  exist? 
What  is  the  composition  of  sillimanitc  ? 


262  MINERALOGY. 

ble  variety,  including  some  kinds  of  lithomarge,  fuller's  earth, 
bole,  cimolite,  haloisite,  &c. 

Finite  occurs  crystallized  in  equiangular,  hexagonal  prisms,  of 
a  blackish-green  colour,  imbedded  in  granite ;  and  gieseckite, 
found  in  Greenland,  appears  to  be  a  variety  of  this  mineral. 

b.  Silicates  with  Several  Bases. 

90.  Apophyllite  is  a  hydrated  silicate  of  lime  and  potash;  me- 
sotype,  or  needle  zeolite,  is  a  hydrated  silicate  of  alumina,  lime, 
and  soda,  occurring  in  acicular  tetraedral  crystals,  as  in  the  follow- 
ing figure ;  natrolite  contains  alumina  and  soda,  but  no  lime  ;  and 
pcolicite   and  thomsonite  are  hydrated  silicates  of  alumina  and 
lime.     Analcime  is  a  silicate  of  alumina  and  soda  with  a  small 

quantity  of  lime.     Stilbite  is  a  hydrated  sili- 
cate of  alumina  and  lime,  containing  (accord- 
ing to  Gehlen)  a  little  soda.     Lanmontite,  so 
called  in  honour  of  M.  Gilles  Laumont,  who 
discovered  it  in  the  lead-mines  of  Bretagne, 
differs  from  the  preceding  in  containing  no 
-  •;  ^  soda,  but  some  carbonic  acid  ;  it  is  subject  to 
efflorescence  when  exposed  to  the  air.     Here 
may  be  mentioned  obsidian,  of  a  black  or 
smoke-gray  hue,  massive,  with  a  conchoidal 
fracture ;    pitchstone,  green,  reddish-brown, 
or  nearly  black,  like  pitch ;  and  pearlstone, 
of  a  dark  bluish-gray  colour,  massive,  but  having  a  granular  ap- 
pearance, with  a  shining  lustre. 

91.  Among  the   zeolitic   substances  may  also   be   mentioned 
prehnite,  of  which  there  are  two  principal  varieties,  the  radiated  or 
fibrous,  which  is  of  a  green  colour,  and  the  foliated,  in  thin  tabular 
crystals,  of  a  greenish- white  colour ;  both  consisting  principally 
of  silica,  alumina,  lime,  oxide  of  iron,  and  water,  hf  which  last 
body  the  foliated  prehnite  contains  but  a  minute  quantity  ;  comp- 
tonite,  a  volcanic  substance,  found  lining  the  cavities  in  lava ; 
gmelinite,  or  hydrolite,  and  levine.     In  the  same  family  fe  to  be 
reckoned  the  harmotome,  or  cross  stone,  which  haVrtceived  the 
latter  name  from  the  peculiarity  of  its  crystallization,  and  which 
consists  of  silica,  alumina,  barytes,  and  water ;  and  the  potash 
harmotome,  which  includes  the  Vesuvian  minerals,  styled  zeago- 
nite,  gismondine,  and  abrazite. 

92.  To  the  feldspar  family  belong  several  important  mineral 

Enumerate  some  of  the  minerals  in  which  silicic  acid  is  combined  with 
several  bases. 

What  is  the  appearance  of  obsidian? — of  pitchstone  ? — of  pearlstone  ? 
What  appearance  has  prehnite? 
What  is  the  composition  of  cross  stone  ? 


HORNEBLENDE. 


263 


bodies.  Common  feldspar  is  found  ex- 
hibiting a  diversity  of  colours,  as  white, 
gray,  light  red,  green,  and  blue,  crys- 
tallized in  rhombic  prisms,  variously 
modified,  imbedded  in  granite.  Labrador 
feldspar  is  found  massive  and  compact, 
displaying  a  beautiful  variety  of  opa- 
lescent colours.  Among  the  feldspathic 
minerals  are  adulari,  or  naker  feldspar ; 
cleavelandite  or  albite,  containing  soda ; 
leucite,  or  amphigene ;  and  spodumene  or  triphane,  and  petalite, 
both  aluminous  silicates  of  the  alkali  called  lithia.  Nepheline, 
eleeolite  or  fettstein,  and  wernerite,  which  includes  the  meionite  of 
Vesuvius,  scapolite,  paranthine,  and  dipyre,  are  minerals  more  or 
less  of  an  analogous  nature.  The  feldspars  are  silicates  of  alumina, 
lime,  and  potash. 

93.  The  micaceous  and  talcose  minerals  form  an  interesting  di- 
vision of  substances.  Mica  exhibits  many  varieties,  which,  with 
reference  to  their  chemical  characters,  have  been  divided  into 
potassa-mica,  which  is  by  much  the  most  common ;  magnesia- 
mica,  found  at  Mount  Vesuvius,  and  at  Munroe,  in  the  state  of  New 
York  ;  and  lithia-mica,  or  lepidolite,  sometimes  of  a  beautiful 
peach-red  colour.  Talc  is  found  in  considerable  variety,  as  the 
Venetian  talc,  in  foliated  crystals  of  a  greenish-white  colour,  a 
substance  which  forms  the  basis  of  rouge,  used  as  a  cosmetic  ;  in- 
durated talc  ;  and  agalmatolite,  (talc  graphique  of  Haiiy,)  a  sectile 
mineral,  which  the  Chinese  form  into  cups,  images,  or  other 
figures.  Chlorite  is  a  green  mineral,  crystallized  in  aggregated 
small  modified  rhombic  prisms ;  and  there  are  earthy  and  foliated 
varieties. 

94.  Among  the  amphi- 
bolic minerals,  or  those  of 
the  hornblende  family, 
may  be  noticed  the  com- 
mon, the  basaltic,  and  the 
schistous  hornblende;  the 
antinolite,  or  strahlstein, 
divided  into  the  glassy, 
the  common,  and  the 
fibrous  varieties ;  the  tre- 
molite,  or  grammatite, 
common  and  glassy ;  the 
arfvedsonite ;  and  the  an- 
thophyllite,  which  con- 
tain silica,  magnesia,  and 

What  are  some  of  the  varieties  found  in  feldspar  ? 

What  bases  are  conlained  in  feldspar? 

What  are  the  chemical  varieties  found  in  mica  and  talc  ? 

What  differences  ot  colour  and  crystalline  form  do  minerals  of  this  class 
pvhibit?  What  are  some  of  the  most  important  of  the  hornblende  family 
of  minerals  ? 


264  MINERALOGY. 

oxide  of  iron  or  lime  ;  and  most  of  them  likewise  contain  alu- 
mina. 

95.  Serpentine,  of  which  there  are  the  noble  and  common  varie- 
ties, exhibits  various  colours,  green,  brown,  and  red,  often  inter- 
mixed ;  and  serpentine-marble  is  ornamented  with  waving  lines,  as 
represented  in  the  preceding  figure.  Chrysolite  and  olivine,  like 
serpentine,  are  coloured  by  oxide  of  iron. 

90.  The  asbestine  minerals  in  their  chemical  composition  are  re- 
lated to  the  preceding.  Among  the  most  remarkable  iprieties 
may  be  mentioned,  the  flexible  asbestus,  or  amianthus,  used  in 
making  incombustible  cloth ;  mountain  wood,  rock  cork,  and  the 
blue  and  yellow  asbestus,  from  South  Africa,  called  krokydalite. 

97.  The  pyroxenic  minerals  are  numerous,  including   augite, 
found   in   small  black  crystals,  imbedded  in  lava,  the  granular 
variety  of  which   is  called  coccolite  ;    diopside,  including  the 
mussite  and  the  alalite,from  Piedmont ;  the  pyrgomme,  or  fassaite, 
which  differs  from  augite  in  the  form  of  its  secondary  crystals; 
and  the  achmite.  To  these  may  be  added  the  diallage,  or  schiller- 
spar,  of  a  green,  brown,  or  black  colour,  and  having  a  metallic 
lustre  ;  the  bronzite,  having  much  the  colour  and  lustre  of  bronze; 
and  the  hypersthene,  tinted  with  a  mixture  of  brown,  black,  and 
copper  colour,  and  exhibiting  considerable  metallic  lustre. 

98.  The  epidote  is  a  mineral  of  a  green  colour,  massive  or  in 
large  crystals,  containing  silica,  alumina,  lime,  and  oxide  of  iron  ; 
and  some  varieties  also  afford  oxide  of  manganese.     Zoisite  re- 
sembles epidote  in  its  chemical  constitution,  but  it  is  generally  of 
a  bluish  or  yellowish-gray  colour.     Idocrase,  or  vesuvian,  is  of 
the  colour  of  brown  resin,  and  of  a  shining  lustre,  and  is  found  in 
prysmatic  crystals,  among  substances  ejected  from  volcanos ;  and 
of  a  similar  composition  is  the  hessonite,  or  cinnamon-stone  ;  both 
these  minerals  containing  silica,  alumina,  lime,  and  oxide  of  iron. 
Cyprine  is  a  variety  of  the  idocrase,  tinted  blue  by  the  oxide  of 
copper. 

99.  The  garnet  family  contains  numerous  and  diversified  varie- 
ties, which  are  silicates  of  alumina,  tinged  with  oxide  of  iron  or 
other  metals.    The  pyrope,  or  chrome  garnet,  of  a  dark  cherry-red 
colour,  occurs  in  rounded  and  angular  concretions,  and  likewise 
imbedded    in   serpentine   and   other  rocks ;   the  colophonite,  so 
named  from  its  resembling  resin  in  colour  and  lustre,  contains 
oxide  of  manganese,  and  a  minute  quantity  of  oxide  of  titanium  ; 
the  melanite,  or  black  garnet,  according  to  Klaproth,  is  an  alumi- 
nous silicate  of  lime  and  iron,  with  a  trifling  proportion  of  oxide 
of  manganese ;  the  grossular,  or  wilui  garnet,  so  called  from  the 
resemblance  of  its  yellowish-green  crystals  to  a  gooseberry,  is 
nearly  of  similar  chemical  composition  ;  the  allochroite,  or  splintery 
garnet,  is  not  so  hard  as  quartz,  but  strikes  fire  with  steel,  and 

What  appearance  is  exhibited  by  serpentine  ? 

Enumerate  some  of  the  varieties  of  pyroxenic  minerals. 

What  materials  enter  into  thf  composition  of  epidote? 

Where  is  idocrase  found  ?     What,  is  the  colouring  matter  of  garnets  ? 

Whence  does  the  colophonite  derive  its  name  ? 


EMERALD.  265 

melts  before  the  blowpipe  into  a  black  enamel ;  it  contains  oxide 
of  manganese,  as  well  as  oxide  of  iron,  in  considerable  proportions  $ 
and  analogous  to  these  is  the  romanzovite. 

100.  The   gehlenite,    so   called    from    Professor   Gehlen,   an 
eminent  mineralogist,  is  found  in  square  prismatic  crystals,  of  a 
light  gray,  olive-green,  brown,  or  bluish-black  colour.     The  iolite, 
or'dichroite,  is  so  called  from  its  different  appearance  when  viewed 
in  different  positions,  generally  exhibiting  a  dull  violet,  or  indigo 
colour  ;  but  if  viewed  by  transmitted  light,  in  the  direction  of  the 
axis  of  the  crystals,  it  appears  of  a  pale  yellowish-brown,  or  gray 
hue;  and  it  occurs  massive,  or  crystallized  in  hexaedral  prisms: 
according  to  the  analysis  of  Dr.  Leopold  Gmelin,  it  is  an  aluminous 
silicate  of  magnesia  and  oxide  of  iron,  with  small  quantities  of 
lime  and  oxide  of  manganese.     Karpholite  is  a  mineral  of  a  deep 
straw  colour,  in  radiated  fibres  or  tufts ;  it  has  only  been  found  at 
Schlackenwald,  in  Bohemia,  and  it  appears  to  be  a  hydrated  silicate 
of  alumina,  and  the  oxides  of  iron  and  manganese. 

101.  Staurolite,   cross-stone,  or   granatite,  is   a  bisilicate   of 
alumine  and  oxide  of  iron. 

Among  the  silicates  containing1  yttria  and  protoxide  of  cerium 
are  the  gadolinite,  a  very  dark  green  mineral  of  a  shining  lustre, 
as  hard  as  quartz,  found  at  Ytterby,  in  Sweden  ;  allanite,  a  brown- 
ish, shining  mineral,  from  Greenland  ;  cerite,  of  a  reddish-brown 
or  crimson  colour,  found  massive  and  disseminated  ;  orthite,  which 
resembles  gadolinite,  but  occurs  in  thin  veins  in  granite,  and  con- 
tains, besides  yttria  and  oxide  of  cerium,  oxide  of  manganese, 
alumina,  lime,  and  water  ;  and  the  variety  called  pyrorthite,  which 
inflames  before  the  blowpipe,  containing  one-fourth  of  carbon. 

102.  The  silicates,  containing  oxide  of  glucinum,  (glucina,) 
constitute  a  division  of  gems,  including  the  emerald.  The  emerald 
is  found  chiefly  in  Peru,  crystallized  in  regular  hexaedral  prisms, 
of  a  fine  green  colour,  which  it  derives  from  oxide  of  chrome.  The 
beryl  occurs  in  primitive  rocks  in  various  parts  of  the  world,  but 
especially  in  Siberia,  resembling  in  the  form  of  its  crystals  the 
emerald,  but  of  a  pale  green  or  blue  colour,  containing  oxide  of 
iron,  instead  of  oxide  of  chrome.     Very  large  beryls  have  been 
found  at  Limoges,  in  France,  and  at  Ackworrh,  in  New  Hamp- 
shire ;    some  crystals   weighing   more   than    fifty  pounds.     The 
euclase  is  a  very  scarce  mineral,  found  in  Peru  and  Brazil,  of  a 
pale  or  bluish-green  colour,  crystallized  in  rhombic  prisms  ;  and, 
according  to   Berzelius,   consisting'  entirely  of  silica,   alumina, 
ancl  glucina.     The  chrysoberyl,  or  cymophane,  occurs  crystallized 
in  tetraedral  prisms,  and  variously  modified,  of  a  pale  yellowish- 
green  colour;  and  it  is  an  aluminons  silicate  of  lime,  coloured  by 
oxide  of  iron. 

What  peculiar  appearance  is  exhibited  by  the  dichroite  ? 

What  is  its  chemical  composition  ? 

What  are  the  characters  of  gadolinite  ? 

What  peculiarity  belongs  to  pyrorthite  ?    Wliere  is  the  emerald  found  ? 

In  what  localities  is  the  beryl  found  ? 


266  MINERALOGY. 

103.  Lazulite,  or  lapis  lazuli,  is  the  mineral  which  furnishes 
the  pigment  called  ultramarine ;  according  to  an  analysis  of  Kla- 
proth,  it  contains  silica,  alumina,  lime,  sulphate  of  lime,  and  oxide 
of  iron,  to  which  last  it  was  supposed  to  owe  its  azure  colour;  but 
it  appears,  from  the  more  recent  researches  of  Gmelin,  that  ultra- 
marine is  a  double  silicate  of  alumina  and  soda,  coloured  by  com- 
bining with  sulphuret  of  sodium,  and  it  has  accordingly  been 
artificially  manufactured   in  France,  in  large  quantities.     Lapis 
lazuli  is  found  in   rolled   pieces,  in  various   oriental    countries. 
Ha;  yne,  or  latialite,  is  a  mineral  of  somewhat  analogous  compo- 
sition,  containing,  according  to  Vauquelin,  silica,  alumina,  lime, 
and  sulphate  of  potash,  with  a  small  quantity  of  oxide  of  iron,  and 
a  considerable  proportion  of  some  volatile  matter.     It  exhibits 
various  shades  of  blue,  and  is  found  imbedded  in  basaltic  and 
feldspathic  rocks,  in  granular  c6ncretions,  and  also  crystallized  in 
rhombic  dodecaedrons. 

104.  Sodalite,  so  named  from  its  containing  a  large  "proportion 
of  soda,  amounting  to  a  fourth  part  of  the  mineral,  is  of  a  dark 
green  colour,  massive,  or  crystallized  in  rhomboidal  dodecaedrons, 
imbedded  in  white  feldspar.     It  has  only  been  found  in  West 
Greenland,  and  since  on  Mount  Vesuvius.  Eudialyte  is  a  silicate 
of  soda,  lime,  and  zirconia,  with  oxide  of  iron,  oxide  of  manganese, 
muriatic  acid,  and  water. 

105.  The  tourmalines  and  schorls,  with  their  varieties,  might 
be  placed  with  the  borates,  as  they  contain  boracic  acid.     The 
rubellite  is  a  beautiful  variety  of  the  tourmaline,  cf  a  pale  pink 
colour,  sometimes  imbedded  in  quartz.     One  of  the  finest  speci- 
mens known  of  this  mineral,  in  which  the  crystals  are  arranged  in 
a  radiated  form,  is  preserved  in  the  British  Museum.     There  are 
also  red  and  blue  varieties  of  the  rubellite,  chiefly  from  Massa- 
chusetts, and  from  Siberia;  flesh-coloured  tourmalines  are  found 
at  Rozena,  in  Moravia ;  to  which  may  be  added  the  dark  green 
variety,  called  the  Brazilian  emerald ;  and  the  asparagus  green  in 
dolomite,  from  Campo  Longo. 

106.  Common  schorl  occurs  in  black  acicular  crystals,  distinct 
and  aggregated,  imbedded  in  quartz  or  feldspar.    Black  schorl  is, 
in  various  forms,   found  abundantly   disseminated  through   the 

granites.  A  specimen  of  green 
tourmaline,  analyzed  by  Gme- 
lin, was  found  to  contain,  be- 
sides silica  and  alumina,  oxides 
of  iron  and  manganese,  boracic 
acid  and  lithion ;  red  tourmaline 
was  found  to  be  an  aluminous 

What  is  the  constitution  of  lapis  lazuli  ? 

What  advantage  has  arisen  from  an  accurate  analysis  of  this  mineral? 

In  what  situations  is  latialite  found  ? 

What  is  socialite  and  eudialite  ? 

In  what  class  of  bodies  are  we  to  place  the  tourmalines  and  schorls  ? 

What  constituents  did  Gmelin  find  in  green  tourmaline  ? 


TITANITE.  267 

silicate  of  potash,  and  oxide  of  manganese,  with  boracic  acid  and 
lithion ;  and  black  schorl  contains  silica,  alumina,  potash,  soda, 
oxides  of  iron  and  manganese,  and  boracic  acid  and  magnesia. 
Axinite  is  a  mineral  of  somewhat  analogous  composition,  contain- 
ing silica,  alumina,  lime,  and  the  oxides  of  iron  and  manganese. 
It  occurs  in  thin  flat  crystals,  the  primitive  form  of  which  appears 
to  be  a  right  prism  with  a  rhombic  basis,  of  a  clove-brown  colour, 
sometimes  very  pale,  and  sometimes  approaching  to  gray.  Beauti- 
ful large  transparent  crystals  are  found  at  Bourg  POisans,  in 
Dauphine,  in  France. 

107.  The  topaz  family  constitutes  an  abundant  division  of  the 
minerals,  containing  silica  and  alumina:  and  from  the  large  pro- 
portion of  fluoric  acid,  which  they  also  generally  afford,  they  might 
perhaps,  without  impropriety,  be  reckoned  among  the  fluorides. 
The  characteristic  colour  of  the  topaz  is  yellow,  but  this  gem  is 
also  found  pink,  blue,  or  colourless.     It  is  found  crystallized,  in 
rhombic  prisms,  with  pyramids,  variously  modified,  and  its  cross 
fracture  is  always  foliated.     The  topaz  is  said  to  be  the  most 
widely  distributed  among  the  precious  stones,  occurring  not  only 
in  Brazil,  but  also  in  New  South  Wales,  in  Siberia  and  various 
other  parts  of  Asia,  in  Saxony,  in  Scotland,  and  at  St.  Michael's 
Mount,  in  Cornwall. 

108.  The  pyrophysalite  is  found  of  a  greenish-white  colour,  in 
irregular  prisms,  imbedded  in  quartz.  The  pycnite,  formerly  con- 
sidered improperly  as  a  variety  of  the  beryl,  occurs  in  thin,  pris- 
matic concretions,  which   are  sometimes   hexagonal,  exhibiting 
either  a  pale  lilac,  a  sulphur  yellow,  or  a  light  straw  colour. 
These  two  last  mentioned  minerals,  like  the  topaz,  are  compounds 
of  alumina,  silica,  and  fluoric  acid. 

Oxide  of  Titanium  and  Titanates. 

109.  Titanium  is  found  in  the  state  of  oxide  in  various  parts  of 
the  world,  either  in  alluvial  strata,  or  imbedded  and  crystallized. 
Rutile,  or  rutilite,  also  called  titan  schorl,  is  a  brownish-red  mine- 
ral, with  a  semi-metallic  lustre,  which  occurs  massive,  and  in  rhom- 
bic tetraedral  prisms ;  it  is  also  found  in  capillary  crystals,  often 
curved,  and  crossing  each  other  in  all  directions.  Acicular  and  ca- 
pillary crystals  of  rutile  have  been  found  inclosed  in  rock-crystal, 
in  Brazil  and  elsewhere.  This  mineral  appears  to  consist  of  per- 
oxide of  titanium.    Anatase,  or  octaedrite,  which  is  found  in  blue 
or  party-coloured  long  octaedral  crystals,  at  Bourg  1'Oisans,  ge- 
nerally associated  with  quartz  and  adularia,  is  a  protoxide  of  tita- 
nium. 

110.  Sphene,  or  titanite,  is  a  combination  of  the  oxide  of  tita- 

What  is  the  composition  and  character  of  axinite  ? 

What  two  ingredients  constitute  the  chief  part  of  the  topaz  minerals? 

What  is  the  composition  of  pyrophysalite  and  pycnite  ? 

What  in  the  chemical  nature  of  rutilite  ? — of  anatase  ? 


268  MINERALOGY. 

nium  with  silica  and  lime,  which  occurs  imbedded  in  very  oblique 
tetraedral  prisms,  with  diedral  terminations,  wedge-shaped  in 
each  direction.  Among  the  varieties  of  this  mineral  are  those  call- 
ed brown  and  yellow  menachan  ore,  in  large  crystals,  found  at 
Arendahl,  in  Norway  ;  and  pale  green  crystals,  containing  chlo- 
rite disseminated  through  them  from  Mount  St.  Gothard.  Pyro- 
chlore,  from  Fredriksvarn,  in  Norway,  is  a  compound  of  titanate 
of  lime  with  titanate  of  uranium.  Nigrine  is  of  a  velvet-black 
colour,  and  is  found  in  rounded  and  angular  grains,  having  a 
semi-metallic  lustre.  Iserine  and  menachanite  have  the  appear- 
ance of  black  sand,  slightly  magnetic.  These  three  last  men- 
tioned minerals  appear  to  consist  chiefly  of  the  oxides  of  titanium 
and  iron  ;  though,  according  to  Dr.  Thomson,  iserine  contains  also 
a  considerable  proportion  of  silica,  with  some  alumina  and  oxide 
of  uranium.  Crichtonite  is  a  silicate  of  titanium,  which  is  found 
in  small,  black,  shining  crystals  with  anatase. 

Columbic  Add  and  Columbates. 

111.  Tantalite,  or  columlite,  is  a  mineral  of  a  black  colour, 
which  crystallizes  in  oblique  rhomboidal  prisms,  and  which  is 
very  rare,  having  only  been  found  in  North  America  and  in  Bava- 
ria.    It  appears  to  consist  of  the  oxides  of  columbium,  iron,  and 
manganese.     Yttrotantalite,  found  at  Ytterby,  in  Sweden,  is  com- 
posed of  oxide  of  columbium,  yttria,  and  iron.  Among  the  mine- 
rals which  contain  the  oxide  of  columbium  are  also  the  finbo  and 
the  brodbp-tantalites  of  Berzelius. 

Antimonic  Oxide  or  Jldd^  and  rfntimoniates. 

112.  Among   the  oxides  of  antimony  are   antimony  ochre,  a 
straw-coloured  mineral,  often  coating  grey  antimony,  which  eva- 
porates before  the  blowpipe  without  melting ;  and  white  antimony 
which  occurs  in  tetraedral    flat  crystals,  or  in  tufts  of  delicate 
fibres,  on  quartz,  galena,  &c.  Red  antimony,  found  in  fine  capilla- 
ry crystals,  stellated,  of  a  red  or  tarnished  purple  colour,  is  a 
combination  of  the  oxide  of  this  metal  with  the  sulphuret ;  and  an 
argentiferous  variety,  of  a  fibrous  texture,  and  reddish-brown  co- 
lour, called  tinder  ore,  is  found  in  the  Hartz  mines,  in  Germany. 

Tungstates. 

113.  Tungsten  is  found  only  in  such  a  state  of  union  with  oxy- 
gen and  other  bodies,  as  to  constitute  mineral  salts    called  tung- 

What  is  the  composition  of sphene? 

What  compound  of  titanium  is  found  in  Switzerland  ? 

What  ingredients  enter  into  the  mineral  iserine? 

Where  is  columbite  found  ? 

What  oxides  of  antimony  are  found  in  nature? 

Where  is  tinder  ore  obtained  ? 


CHRCMATE  OF  LEAD.  269 

states  ;  the  compound  of  this  metal  with  oxygen,  as  it  occurs  natu- 
rally, having  the  properties  of  an  acid,  and,  as  such,  entering  into 
combination  with  the  oxides  of  certain  other  metals. 

114.  The  tungstate  of  lime  (scheelin  calcaire  of  Hauy,)  alsf>  na- 
named  scheelite  or  tungsten,  and,  from  its  great  specific  gravity, 
heavystone,  is  a  whitish  or  yellowish-brown  mineral,  which  is 
found  massive,  or  crystallized  in  octaedrons,  coating  other  sub- 
stances, in  England,  France,  Saxony,  Bohemia,  and  Sweden.  Spe- 
cimens of  the  primitive  (octaedral)  crystal  of  this  metallic  salt  are 
obtained  at  Allemont,  in  Dauphine.     The  tungstate  of  iron  and 
manganese  called  wolfram,  occurs  in  the  massive  form,  or  crys- 
tallized in  tetraedral  tables,  variously  modified  ;  hard  and  brittle, 
of  a  colour  almost  black,  and  a  metallic  lustre,  but  it  soon  tar- 
nishes ;  it  abounds  in  Cornwall,  and  is  generally  found  in  conjunc- 
tion with  the  ores  of  tin,  in  primitive  formations.  The  only  other 
native  tungstate  hitherto  discovered,  is  that  of  lead,  occuring  at 
Zinnwald,  in  Bohemia,  and  which  was  formerly  mistaken  for  a 
molybdate  of  lead. 

Moli/bdic  Acid  and  Molybdates. 

115.  Molybdena,  like  tungsten,  forms  an  acid  with  oxygen,  and 
mineralizes  other  metals. 

Ochry  Molybdena,  which  is  found  in  Sweden  and  elsewhere,  in 
the  state  of  a  yellow  powder  incrusting  feldspar,  or  the  native 
sulphuret  of  molybdena,  appears  to  consist  of  the  acid  of  this 
metal.  Molybdate  of  lead  occurs  massive,  disseminated,  and 
foliated,  or  in  lamellar  hexaedral  crystals,  exbiting  various  tints 
of  yellow.  It  was  first  found  in  Carinthia,  and  has  been  since  met 
with  in  Hungary,  Austria,  Saxony,  Mexico,  and  Massachusetts, 
frequently  imbedded  in  quartz. 

Chromic  Jicid  and  Chromates. 

116.  Chrome,  or  chromium,  is  another  acidifiablc  metal,  though 
the  chromic  acid  has  not  yet  been  found  in  a  native  state. 

Protoxide  of  chrome  has  been  discovered  in  the  department  of 
the  Rhone,  in  France,  forming  a  green  incrustation  on  other 
minerals,  and  it  constitutes  the  colouring  matter  of  the  emerald. 

117.  Chromate  of  lead,  or  Siberian  red  lead  ore,  occurs  in  the 
gord  mines  of  Beresof,  in  a  kind  of  micaceous  rock,  mingled  with 

In  what  state  does  tungsten  occur  in  nature  ? 
What  properties  does  its  compound  with  oxygen  possess? 
Bv  what  names  is  the  tungstate  oflime  known? 
Where  is  tungstate  of  iron  met  with  ? 
What  other  salt  of  tungstic  acid  has  been  discovered  ? 
What  is  the  character  of  the  compound  of  molybdena  and  oxygen? 
What  is  the  chemical  nature  of  ochry  molybdena? 
In  what  form  does  molybdate  of  lead  present  itself? 
In  what  mineral  is  protoxide  of  chrome  discovered  ? 
z  2 


270  MINERALOGY. 

particles  of  quartz  and  brown  ironstone,  forming-  prismatic  crystals 
of  a  deep  orange  colour,  and  sometimes  accompanied  by  small 
green  crystals,  which  are  supposed  to  be  chronite  of  lead,  or  a 
compound  of  the  oxides  of  chrome  and  lead.  Vauquelinite,  a 
mineral  accompanying  the  red  lead  ore  of  Siberia,  is  a  chromate 
of  lead  and  copper.  Chromate  of  iron,  containing  also  alumina 
and  silica,  has  been  found  in  France,  in  Maryland,  and  also  in 
some  places  in  Siberia,  massive,  or  in  octaedral  crystals,  of  a 
black  or  bluish-black  colour. 

Vanadic  Add  and  Vanadiates. 

118.  Vanadium  being  one  of  those  metals  that  combine  with 
oxygen  in  different  proportions,  forming  acids  as  well  as  oxides, 
it  enters  into  union  with  the  oxides  of  other  metals. 

This  metallic  substance  was  discovered  in  1830,  by  Sefstrom, 
a  Swedish  chemist,  in  a  kind  of  iron  ore  found  at  Taberg,  in  Srno- 
land,  but  it  has  not  been  ascertained  in  what  state  the  vanadium 
exists  in  that  ore.  Shortly  after  the  metal  had  been  observed  in 
Sweden,  Mr.  J.  W.  F.  Johnston,  of  Edinburgh,  found  the  vana- 
diate  of  lead  in  a  mineral  from  the  mines  of  Wanlock  Head,  in 
which  the  vanadium  constituted  the  principal  electro-negative  in- 
gredient, though  chlorine,  and  the  arsenic  and  phosphoric  acids 
were  likewise  present.*  There  are  at  least  two  varieties  of  the 
Wanlock  Head  mineral ;  the  first  resembling  arseniate  of  lead, 
occurring  in  mammillary  tufts  on  the  surface  of  calamine,  and 
sometimes  passing  into  the  chrystalline  form;  the  other  found 
amorphous,  or  in  small  round  spots,  of  a  black  colour,  like  oxide 
of  manganese,  coating  the  calamine,  or  dispersed  in  cavities.  Pro- 
fessor Del  Rio  had  previously  found  the  vanadic  acid  combined 
with  oxide  of  lead,  in  brown  lead  ore,  from  Zumpan,  in  Mexico, 

Boracid  Add  and  Borates. 

119.  Boratic  add  is  found  existing  in  nature   in  the  Lipari 
Islands,  and  likewise  in  the  hot  springs  of  Sasso,  in  Tuscany, 
whence  the  term  sassoline  has  been  applied  to  it  by  some  mineral- 
ogists.    It  occurs  likewise  in  light  crusts  on  substances  in  the 
neighbourhood  of  extinct  volcanos. 

120.  Borax,  called  also  tincal,  is  a  native  borate  of  soda,  found 
in  Thibet,  Persia,  Tuscany,  and  it  is  said  also  in  Peru  and  China. 
Boradte,  or  borate  of  magnesia,  occurs  crystallized  in  cubes,  and 

With  which  of  the  metals  does  chromic  acid  combine  ? 

Where  in  the  United  States  does  chromate  of  iron  occur  ? 

By  whom  was  vanadium  first  conclusively  shown  to  be  a  distinct  element? 

In  what  combinations  was  it  found  by  Sefstrom  ? 

Where  have  vanadiates  of  lead  been  discovered  ? 

In  what  regions  is  native  boracic  acid  found  ? 

What  chemical  compound  is  native  borax  ? 

*  JRejport  of  the  British  Association  for  1832,  p.  470. 


ARRAGONITE.  271 

variously  modified,  of  a  light  gray  colour,  opaque  or  translucent, 
and  the  crystals  are  found  imbedded  in  gypsum  near  Kiel  in  Hoi- 
stein,  and  at  Luneberg  in  Hanover.  Datolite,  a  mineral  of  a  pale 
greenish-white  colour,  massive  or  crystallized  in  cubes,  sometimes 
modified,  is  found  at  Arendahl,  in  Norway ;  whence  also  is  ob- 
tained a  globular  fibrous  variety  called  botryolite :  both  these 
minerals  contain  boracic  acid  combined  with  silica  and  lime. 
V 

Carbonates. 

121.  Carbonate  of  soda  is  found  in  some  mineral  waters,  and 
most  abundantly  in  the  lake  called  Lagunilla,  in  Venezuela,  from 
which  the  salt  is  procured  as  an  article  of  commerce.     A  combi- 
nation of  the  carbonate  and  bicarbonate  of  soda  is  obtained  in  large 
quantities  in  the  saline  state,  from  the  oasis  of  Gadamis,  west  of 
Fezzan,  in  Africa,  where  it  is  called  trona.     According  to  an 
analysis  made  by  Mr.  Richard  Phillips,  it  consists  of  three  parts 
of  acid  and  two  of  soda,  and  hence  he  terms  it  a  sesqui-carbonate 
of  soda. 

122.  Strontianite  is  a  rare  mineral,  of  a  greenish  colour,  found 
in  radiated  masses,  and  sometimes  in  acicular  hexaedral  crystals, 
generally  imbedded  in  earthy  barytes,  and  associated  with  galena ; 
it  was  first  obtained  from  Strontian,  N.  B.,  and  has  since  been 
discovered  in  Saxony,  in  Peru,  and  in  Pennsylvania.    Witherite, 
or  carbonate  of  barytes,  occurs  in  large  masses  in  diverging  fibres 
or  crystallized  in  hexaedral  prisms  and  pyramids  ;  forming  some- 
times beautiful  groups  of  double  pyramidal  crystals,  the  primitive 
form  of  which  is  an  obtuse  rhomboid.     It  has  been  found  in  Lan- 
cashire, and   other  northern   counties  of  England,  and  also  in 
Shropshire  and  in  Wales.     Baryto-calcite,  is  a  compound  of  the 
carbonates  of  barytes  and  lime,  which  occurs  in  Cumberland,  and 
was  at  first  supposed  to  be  a  variety  of  carbonate  of  barytes,  but 
it  differs  in  crystallization,  its  primitive  form  being  an  oblique 
rhombic  prism. 

123.  Carbonate  of  lime. — This  division  of  the  carbonates  com- 
prehends the  multifarious  varieties  of  calcareous  spar,  marble, 
chalk,  and  limestone,  many  of  which  are  much  more  interesting  in 
a  geological  than  in  a  mineralogical  point  of  view,  and  therefore 
will  here  require  but  a  brief  notice. 

124.  Arragonite  is  a  mineral  of  a  white  colour  with  a  pearly 
lustre,  and  sometimes  with  a  reddish  hue,  which  occurs  in  hexae- 
dral crystals,  aggregated,  grouped,  or  imbedded  in  gypsum,  also 
arborescent,  dendritic,  or  stalactitic,  and  likewise  in  acicular  fibres, 
one  variety  of  which  has  been  called  flos  ferri,  from  its  resemblance 

What  is  the  composition  and  form  of  boracite  ?    Whence  is  it  found  ? 

Where  is  native  carbonate  of  soda  found? 

In  what  locality  does  the  sesqui-carbonate  occur? 

What  is  the  appearance  of  carbonate  of  strontia? 

How  does  witherite  crystallize  ? 

What  classes  of  familiar  substances  are  among  the  carbonates  of  lime  ? 

What  is  the  external  appearance  of  arragonite  ? 


272 


MINERALOGY. 


to  a  delicate  white  flower.  It  has  been  found  in  Arragon,  Bohemia, 
Styria,  and  France.  Some  specimens  are  found  to  contain  three 
or  four  per  cent,  of  carbonate  of  strontian. 

125.  Calcareous  spar  is  a  carbonate  of  lime  in  transparent  crys- 
tals, the  primitive  form  of  which  is  a  rhomb,  passing  into  almost 
innumerable  varieties ;  its  colour  is  various,  but  it  generally  ex- 
hibits light  tints.     Among  the  sub-varieties  may  be  mentioned  the 
dogtooth  spar,  with  double  hexaedral  pyramids,  joined  at  their 
base,  and  the  short  hexaedral  prismatic  crystals  turned  so  that  the 
lines  of  the  pyramids  correspond.    This  mineral,  frequently  called 

the  Iceland  spar,  is  peculiarly 
interesting,  as  having  furnish- 
ed the  means  for  the  discovery 
of  the  double  refraction  of 
light.  It  is  found  in  Iceland, 
in  the  Hartz  mountains  of 
Germany,  and  in  Derbyshire, 
where  it  occurs  in  large  crys- 
tals, of  a  topaz-yellow  colour; 
and  that  kind  called  fontaine- 
bleau  sandstone,  contains  a 
considerable  admixture  of  quartz. 

126.  Stalactitic  limestone,  formed  by  deposition  from  the  water 
of  springs  holding  carbonate  of  lime  in  solution,  is  of  various 
colours,  as  white,  green,  and  brown,  sometimes  in  the  form  of 

long  tubes,  in  that  of  icicles,  botryoidal 
masses,  and  a  variety  of  other  figures,  one 
of  which  is  represented  in  the  margin.  It  is 
frequently  found  pendant  from  the  roofs,  or 
incrusting  the  walls  of  caverns,  as  in  Derby- 
shire, the  Island  of  Sky,  St.  Michael's  Cave, 
i  Gibraltar,  in  the  famous  Grotto  of  Antiparos 
in  the  Archipelago,  and  in  the  Mammoth 
Cave  of  Kentucky.  Satin  spar  is  a  fibrous 
variety  of  carbonate  of  lime,  of  a  snow-white, 
bluish,  or  green  colour,  which  has  derived 
its  name  from  its  peculiar  pearly  lustre,  and 
which  is  found  in  Cumberland  and  in  Swe- 
den. 

127.  Those  limestones  which  admit  of  being  finely  polished,  are 
generally   termed   marbles,   of   which   there   are   a   great   many 
varieties.    The  white  granular  limestone,  or  marble  of  the  primitive 
rocks,  which  is  the  most  highly  esteemed,  is  to  be  distinguished 
from  the  secondary  limestone  by  the  entire  absence  of  organic  re- 

What  is  the  primitive  crystalline  form  of  calcareous  spar? 
What  is  the  form  of  dogtooth  spar  ? 

What  optical  phenomenon  was  originally  discovered  by  means  of  ice- 
land  spar? 

How  is  stalactite  limestone  produced  ? 
Whence  is  the  term  satin  spar  derived  ? 


CHALK.  273 

mains,  by  its  granularly  foliated  structure,  and  by  its  association 
with  other  primitive  substances.  The  most  valuable  kind  of 
statuary  marble  is  the  Parian,  and  that  of  Mount  Pentelicus,  near 
Athens,  of  which  are  formed  some  of  the  finest  existing  sculptures 
of  antiquity.  The  marble  of  Carrara,  in  Italy,  is  also  celebrated 
for  its  beauty,  having  been  much  employed  by  sculptors.  It  is  of 
a  milk-white  hue,  and  less  crystalline  than  the  marble  of  Paros. 

128.  Many  of  the  varieties  of  figured  and  coloured  marbles 
are  extremely  beautiful,  deriving  their  characteristic  peculiarities 
from  the  admixture  of  various  foreign  bodies.    There  is  a  kind  of 
marble  found  in  Tirey,  one  of  the  Western  Islands  of  Scotland, 
of    a    reddish    colour,    which    contains    sahlite,    and    probably 
titanium  imbedded.    Cipolin  is  a  sort  of  statuary  marble,  with 
veins  of  mica.     Brocatella  is  a  breccia  limestone,  composed  of 
fragments  of  a  yellowish-red  and  purple   colour,  cemented  by 
similar  transparent  calcareous  spar.    Verde  Anticho  and  Verde  di 
Corsica,  are  composed  of  compact  limestone  and  calcareous  spar, 
with  serpentine  and  asbestus ;  and  of  a  similar  nature  is  the  va- 
riety called  Mona  marble. 

129.  Florentine  marble  is  a  grayish  compact  marble,  witb  ar- 
gillaceous earth,  exhibiting  designs  of  landscapes    or   ruins    in 
yellowish-brown  tints.     Lumachella  marble  is  a  compact  lime- 
stone, of  a  brownish-gray  colour,  in  which  shells  are  imbedded. 
Lucullite,  or  black  marble,  containing  carbonaceous  matter,  is 
used  for   ornamental  architecture  and    other   purposes.     Madre- 
porite,  or  prismatic  lucullite,  is  so  called  from  its  resemblance 
in  structure  to  madrepores.     Swinestone,  or  fetid  limestone,  is  a 
variety  containing  bitumen  in  various  proportions,  whence  it  de- 
rives a  fetid  odour.     Much  of  it  is  found  on  the  banks  of  the  river 
Avon,  near  Bristol,  England  ;  and  there  is  a  sectile  variety  met 
with  iu  Dalmatia,  said  to  be  about  the  consistence  of  soap. 

130.  Oolite,  or  roestone,  is  a  variety  of  carbonate  of  lime, 
which  derives  its  appellation  from  its  structure  and  appearance, 
being  composed  of  minute  globular  concretions,  of  a  yellowish- 
brown  or  straw  colour,  much  used  in  building,  under  the  names 
of  Portland  stone  and  Bath  stone.     Pisolite,  or   peastone,  some- 
what resembles  the  preceding,  but  consists  of  larger  concretions, 
composed  of  concentric  layers  surrounding  grains  of  sand,  formed 
by  deposition  from  hot  springs,  as  at  Carlsbad,  in  Bohemia,  and 
at  Tivoli,  in  Italy.   Calcareous  tufa  is  an  earthy  carbonate  of  lime, 
of  a  porous,  spongy   structure,  forming  casts  or  incrustations  by 
deposition  from  water.    Casts  of  medals  have  thus  been  obtained, 
by  placing  them  in  moulds  to  receive  the  spray  impregnated  with 
calcareous  particles,  and  incrustations  of  a  similar   nature   are 

How  is  primitive  distinguished  from  secondary  limestone  ? 
What  localities  are  celebrated  for  furnishing  the  finest  marble  ? 
What  is  the  nature  of  verde  antique  ? 
What  peculiarity  does  the  Florentine  marble  present  ? 
What  occasions  the  odour  of  fetid  limestone  ? 
What  is  the  appearance  of  Portland  stone  ? 

How  is  pisolite  formed  ?     What   imposition   is  practised  at  certain  En- 
glish mineral  springs  by  means  of  calcareous  deposits  ? 


274  MINERALOGY. 

obtained  from  springs  at  Matlock  and  at  Knaresborough,  where 
they  are  sold  as  petrifactions. 

131.  Chalk   and  its  varieties,  rock  milk  and  agaric  mineral, 
are  carbonates  of  lime ;  and  marl  is  chiefly  composed  of  the  same 
substance  mixed  with  argillaceous  earth. 

Carbonate  of  magnesia. — Magnesite,  which  is  a  carbonate  of 
magnesia,  generally  white  and  friable,  or  in  fine  acicular  crystals, 
has  thus  been  found  in  Piedmont,  and  in  Moravia ;  likewise  at 
Hoboken,  in  New  Jersey,  in  veins  in  a  serpentine  rock,  accompa- 
nying the  native  hydrate  of  this  earth ;  and  a  variety  has  been 
obtained  from  the  East  Indies,  which  is  white,  massive,  hard,  of 
a  conchoidal  fracture,  and  translucent  at  the  edges.  The  carbo- 
nate of  magnesia  more  frequently  occurs  combined  with  that  of 
lime,  as  in  the  dolomite,  which  is  of  a  snow  white  colour,  and 
granular  texture,  often  containing  realgar  and  pyrites.  A  variety 
of  dolomite,  found  in  Massachusetts,  and  elsewhere,  exhibits  a 
considerable  degree  of  flexibility.  Rhomb  spar,  or  bitter  spar,  is  a 
mineral  of  a  yellowish  or  brown  colour,  which  occurs,  imbedded  in 
chlorite  schist,  in  the  Tyrol,  at  Saltzburg,  and  in  Sweden.  Miemite, 
tharandite,  and  pearl  spar,  are  varieties  of  magnesian  limestone. 

132.  Among  the  carbonates  of  iron  are  sparry  iron  ore,  of  a 
grayish  or  yellowish-white  colour,  crystallized,  fibrous,  massive, 
and     botryoidal ;    which    last    variety  has  been  termed  spheero- 
siderite.  This  carbonate  has  been  found  in  Cornwall,  crystallized 
in  hexagonal  prisms,  but  its  more  usual  form  is  the  equiaxial  rhomb. 

Carbonate  of  manganese,  is  found  in  globular  or  botryoidal  forms 
of  various  shades  of  rose  colour,  with  sulphuret  of  manganese 
and  oxide  of  iron. 

Calamine,  or  carbonate  of  zinc,  is  found  in  tabulated  crystals, 
generally  tetraedral,  and  in  acute  rhombs,  also  compact,  botryoidal, 
and  in  other  forms,  of  various  shades  of  colour,  generally  either 
green  or  brown. 

p.  133.  Carbonate  of  lead,  or  sparry  lead 

Jf  ore,  exhibits  considerable  variety  of  form. 

The  compact  carbonate,  of  a  snow-white 
or  cream  colour  and  shining,  is  commonly 
associated  with  galena.  It  is  also  found 
semi-translucent,  crystallized  in  double 
hexagonal  pyramids  on  galena ;  and  it 
occurs  in  fibrous  or  canrcnlated  crystals, 
sometimes  coloured  by  green  carbonate 
of  copper.  The  earthy  or  pulverulent 
varieties  are  of  a  brown  or  cream  co- 
lour. 

What  is  the  nature  of  marl? 

Wilh  what  other  carbonate  is  that  of  magnesia  often  associated  ? 

What  is  the  mineralogical  name  of  elaetic  marble  ? 

What  varieties  of  magnesia,  limestone  are  enumerated  ? 

What  is  the  appearance  of  carbonate  of  iron  ? — of  manganese  ? — of  zinc  ? 

In  what  forms  does  carbonate  of  lead  occur  ? 

What  colour  has  it  in  powder  ? 


ARSENIOUS  ACID  AND  ARSENIATES.  275 

134.  Carbonate  of  copper  exhibits 
some  remarkable  -varieties,  some  of 
which  have  been  used  as  pigments 
under  the  name  of  mountain  blue. 
Among  these  carbonates  are  the  vel- 
vet copper  ore,  of  a  brilliant  light  blue 
colour,  found  only  at  Oravitza,  in  the 
Bannat,  forming  a  velvet  incrustation 
on  malachite  and  brown  ironstone.  The 
green  carbonates  include  fibrous  mala- 
chite, occurring  in  acicular  or  fascicular 
and  stellated  crystals,  and  also  foliated  ;  compact  malachite  is 
found  massive,  mammilated,  with  a  zoned  fracture,  or  crystallized 
in  octaedrons  or  dodecaedrons,  detached  or  imbedded  in  red  cop- 
per ore.  This  ore,  of  a  beautiful  green  velvet  exterior,  is  found  in 
Berks  Co.,  Pennsylvania. 

Arsenious  Acid  and  JLrseniates. 

135.  Arsenious  acid. — This  acid  in  the  native  state  called  also 
arsenic  bloom  or  octaedral  oxide  of  arsenic,  has  been  often  con- 
founded with    arseniate  of  lime :  it  occurs  stalactitic,  in  delicate 
flat  crystals  or  in  silky  filaments,  of  a  white  colour,  incrusting 
other  minerals. 

136.  Pharmacolite  is  a  combination  of  arsenious  acid  and  lime, 
found  in  capillary  crystals,  which  look  like  little  tufts  of  cotton. 
Arseniate  of  iron,  or  pharmacosiderite,  is  found  chiefly  in  small 
cubic  crystals  in  the  tin  mines  of  Cornwall,  and  in  other  parts  of 
the  world.     Skorodite,  which  appears  to  be  a  cupreous  arseniate 
of  iron,  is  found  in  minute  blue  or  greenish  rhombic  crystals, 
generally  accompanying  the  preceding  mineral.    There  are  several 
varieties  of  arseniate  of  copper,  as  the  octaedral  arseniate  of  a  sky- 
blue  or  emerald-green  colour,  in  flat  crystals;  the  tabulated  arse- 
niate in  flat  hexaedral  crystals,  of  an  emerald  colour;  thetriedral 
arseniate,  of  a  blackish  or  shining  blue  colour,  crystallized  in  rhom- 
bic prisms,  sometimes  with  diedral  summits,  and  also  flat,  curved, 
aggregated,  and  variously  modified;  and  the  fibrous  arseniate. 

137.  The  arseniates  of  cobalt,  or  red  cobalt  ores,  comprise  the 
earthy  and  the  radiated  varieties,  the  former  of  which  is  a  soft, 
friable  mineral,  of  a  rose  colour,  sometimes  forming  very  small 
botryoidal   concretions   in  the  cavities  of  gray  cobalt ;   and  the 
radiated  variety  consists  of  delicate  acicular  crystals  ;    sometimes 
of  a  stellular  figure,  fonnd  upon  other  minerals  in  Cornwall,  Scot- 
land, Saxony,  Hungary,  and  Norway. 

Arseniate  of  lead  occurs,  in  slender  hexagonal  crystals,  upon 
quartz  and  steatite,  in  Saxony,  Siberia,  and  especially  in  Corn- 
How  does  carbonate  of  copper  crystallize  ?     What  is  meant  by  mala- 
chite ?     In  what  situations  does  arsenious  acid  occur  in  nature  ? 
What  is  the  nature  of  pharmacolite  ? 
What  are  some  of  the  varieties  of  arseniate  of  copper  ? 
What  is  the  colour  of  the  arseniate  of  cobalt  ?    Where  is  it  obtained  ? 


276  MINERALFGY. 

wall.   There  is  a  reniform  arseniate  of  lead  in  lamellar  concretions, 
of  a  yellowish  colour,  found  in  Siberia. 

PhospJiates. 

138.  The  phosphates  of  lime  include  some  varieties.     Apatite 
is  a  mineral  of  a  grayish  or  green  colour,  crystallized  in  hexaedral 
prisms  or  tables,  and  variously  modified.     Some  specimens  are 
found  of  a  violet  colour;  the  green  and  blue  varieties  are  called 
moroxite,  and   the  pale  yellow-green  asparagus-stone,  and   this 
phosphate  is  sometimes  found  of  a  snow-white  colour.     Phos- 
phorite, formerly  supposed  to  be  of  the  same  composition,  with 
fluor  spar,  is  a  phosphate  of  lime,  generally  of  a  light   reddish 
brown  or  whitish  and  yellowish  colour,  in  distinct  concretions, 
earthy  or  massive,  found  in  Hungary  and  elsewhere. 

139.  Phosphate  of  lead,  or  pyromorphite,  is  found  massive, 
crystallized  in  hexaedral  prisms,  dendritic,  or  earthy  and  friable, 
of  a  green  and  yellow  colour;  and  also  in  hexagonal  prisms  and 
acicular  crystals,  of  a  deep  orange  or  brown  colour. 

Phosphate  of  yttria,  or  phosphyttrite,  is  a  very  scarce  mineral, 
first  found  in  granite,  at  Lindenas,  in  Norway;  and  afterwards, 
in  similar  small  quantities,  at  Ytterby,  in  Sweden. 

140.  Phosphate  of  iron   occurs  in  rhombic  prisms,   striated, 
acuminated,  and  variously  modified,  of  a  green  colour ;  it  is  alsa 
sometimes  found  of  a  blue  colour,  and  likewise  black.     These 
varieties,  except  the  last,   have  been  found  in    Cornwall ;   the 
earthy,  blue  iron  ore,  and  wood,  peat,  and  clay,  impregnated  with 
this  mineral,  have  been  met  with  in  New  Jersey.* 

Phosphate  of  manganese,  or  triplite,  is  a  mineral  of  a  shining 
black,  or  brownish-black  colour,  which  rnelts  before  the  blowpipe 
into  a  black  enamel. 

Phosphate  of  copper  has  been  found  near  Cologne,  in  Germany, 
of  a  green  colour,  in  small  rhomboidal  crystals.  Among  the 
varieties  of  this  phosphate  may  be  specified  the  olive  malachite, 
or  octaedral  phosphate,  found  at  Lebethen,  in  Hungary;  and  the 
prismatic  variety,  called  pseud*  o  mala- 
chite, from  Rheinbreitenbach,  where  it 
is  found  with  quartz,  sometimes  passing 
into  calcedony. 

141.  Phosphate  of  alumina  appears  to 
form  the  basis  of  several  minerals,  the 
composition  of  which,  however,  has  not 
been  perfectly  ascertained.  Among  these 
are  the  wavellite,  formerly  called  hydrar- 
gillite,   found   in    Devonshire,    Ireland, 
Bavaria,  Bohemia,  Greenland,  and  Bra- 
Enumerate  and  describe  the1  native  phosphates  of  lime  ? 
What  is  the  number  of  sides  in  prismatic  phosphate  of  lead  ? 
What  variety  of  colour  docs  it  exhibit  ?     What  is  the  form  of  the  crys- 
tals of  phosphate  of  iron  ?    Wliat  is  the  composition  of  wavellite  ? 

*  See  Morton's  Organic  Remains,  p.  16. 


CELESTINE.  277 

zil,  forming  globular  concretions,  or  fibrous  and  radiated  groups ; 
the  klaprothite,  called  also  blue  spar,  or  azurite ;  the  calaite,  or 
real  turquois,  an  opaque  gem  found  principally  in  the  province  of 
Khorasan,  in  Persia,  imbedded  in  a  ferrugino-argillaceous  rock; 
the  kakoxene,  a  rare  substance  found  in  Bohemia,  in  the  fissures 
of  argillaceous  ironstone,  and  exhibiting  a  crystalline  fibrous 
structure,  and  a  yellow  colour ;  and  the  childrenite,  found  at 
Tavistock,  in  Devonshire. 

142.  The  phosphate  of  uranium  includes  the  yellow  uranite,  or 
uran  mica,  found  in  France,  in  thin,  quadrangular  crystals ;  and 
the  green  uranite,  or  chalcolite,  in  tetraedral  tables,  aggregated  and 
detached,  or  elegantly  grouped,  which  has  been  obtained  chiefly 
from  Cornwall  and  from  Saxony. 

Nitrates. 

143.  Nitrate  of  potash,  or  native  saltpetre,  is  found  as  an  efflo- 
rescence, consisting  of  capillary  crystals,  incrusting  chalk  and 
limestone  rock,  at  Polo  di  Molfetta,  in  Apulia  in  Italy,  near  Bur- 
gos in   Spain,  and  elsewhere.     In  the  vicinity  of   Evreux,  in 
France,  nitre  is  collected  from  the  surface  of  the  calcareous  soil 
several  times  in  the  year;  and  it  is  obtained  largely  in  the  same 
manner,  for  the  purposes  of  commerce,  in  the  East  Indies  and 
other  parts  of  the  world. 

Nitrate  of  lime  is  often  found  combined  with  that  of  potash,  and 
may  sometimes  be  observed  forming  silky  efflorescences  on  old 
walls ;  it  likewise  occurs  in  some  mineral  waters. 


Sulphates. 

144.  The  sulphates  are  a  numerous  class  of  minerals,  including 
many  of  the  soluble  salts.     Sulphate  of  soda,  or  glauber  salt,  is 
frequently  found  as  an  efflorescence,  and  sometimes  in  acicular 
crystals,  near  mineral  springs  and  salt  lakes.     Thenardite  is  a 
hydrous  sulphate  of  soda,  found  in  crystalline  crusts  at  the  bot- 
tom of  the  briny  waters  at  the  Salines  d'Espartines,  in  the  neigh- 
bourhood of  Madrid.     Glauberite  is  a  mineral  composed  of  the 
anhydrous  sulphates  of  soda  and  lime,  found  imbedded  in  salt 
and  clay  in  the  salt-mines  of  Villarubia  and  Aranjuez,  in  Spain. 
Reussite  is  a  sulphate  of  soda,  combined  with  sulphate  of  mag- 
nesia. 

145.  Celestine,  or  sulphate  of  strontian,  a  mineral  of  which  there 
are  several  varieties,  is  found  near  Bristol,  England,  in  France,  the 

Where  is  calaite  found  ? 
In  what  localities  has  uranite  been  obtained  ? 
What  are  the  two  nitrates  which  occur  in  a  mineral  form  ? 
In  what  forms  does  the  sulphate  of  soda  occur  ? 
What  is  the  mineralogical  name  of  sulphate  of  strontian  ? 
2  A 


278  MINERALOGY. 

Tyrol,  Spain,  Sicily,  and  in  Pennsylvania.  It  occurs  of  a  sky- 
blue  or  gray  colour,  and  sometimes  of  a  white,  yellowish-white, 
or  brown  ;  massive  and  foliated,  in  tabulated  crystals,  in  radiated 
fibres,  or  compact  in  hollow  balls,  with  internal  crystallizations. 

146.  Sulphate  of  barytes,  or  heavy  spar,  exhibits  a  considerable 
variety  of  crystallization,  the  primitive  form  being  a  right  prism 
with  rhombic  bases.     It  forms  large  wax-like,  yellow  crystals, 
and  is  found  in  Cumberland,  at  Schemnitz  in  Hungary,  Clausthal 
in  the  Hartz,  Traversella  in  Piedmont,  and  elsewhere.     The  ra- 
diated or  stellated  variety  of  this 
sulphate  includes  the  Bologna  stone 
of  Monte  Paterno,  used  in  the  pre- 
paration  of  the    Bolognian    phos- 
phorus.     (See    marginal    figure.) 
To  these  may  be  added  the  beauti- 
ful variety  called  chain  spar,  from 
the  Hartz;  the  fibrous  and  the  granu- 
lar varieties ;  the  prismatic  barytes, 
generally  of  a  brown-yellow  colour ; 
the  compact,  called  barytic  or  pon- 
derous  marble;    and    the  fetid  or 
hepatic  barytes,  of  a  smoke  colour, 

which  occurs  massive  and  nodular. 

147.  Sulphate  of  lime  is  found  in  abundance  in  France,  Spain, 
and  other  parts  of  the  south  of  Europe,  exhibiting  some  varieties, 
among  which  may  be  specified  selenite,  or  sparry  gypsum,  in 
hexagonal  prisms,  or  variously  modified,  sometimes  stained  of  a 
yellow  colour  by  oxide  of  iron  ;  fibrous  gypsum,  opaque  or  trans- 
lucent, of  a  snow-white  hue,  with  a  silky  lustre ;  granular  gyp- 
sum, or  alabaster ;   compact  gypsum,  white  or  variegated,  and 
with  red  and  white  veins,  which  variety  includes  the  stalagmitic 
gypsum  of  Guadaloupe.     Anhydrous  sulphate  of  lime,  (likewise 
styled  anhydrite,  cube-spar,  and  muriacite,)  is  composed,  as  its 
name  implies,  of  sulphuric  acid  and  lime,  without  water ;  and  it 
is  found  crystalline,  fibrous,  granular,  and  compact,  chiefly  of  a 
milk-white  or  bluish  colour.     Anhydrous  sulphate  of  lime,  con- 
taining silica,  has  been  found  in  Italy,  where  it  is  called  marmo 
bardiglio  di  bergamo,  and  by  Count  Bournon,  bardiglione;  and  a 
variety  occurs  in  the  salt  mines  of  Wieliczka,  in  Poland,  which, 
from  the  peculiarity  of  its  structure,  is  termed  tripestone.     Much 
of  the  gypsum  used  in  the  United  States  is  imported  from  Nova 
Scotia. 

148.  Sulphate  of  magnesia,  or  Epsom  salt,  which  is  of  common 
occurrence  in  mineral  waters,  as  those  of  Epsom  and  Cheltenham, 

In  what  part  of  the  United  States  may  this  mineral  be  met  with  ? 
What  is  the  primitive  form  of  sulphate  of  barytes  ? 

What  are  some  of  the  varieties  in  the  form  and  other  characters  of  this 
mineral?     In  what  European  countries  is  sulphate  of  lime  found  ? 
What  is  the  chemical  nature  of  alabaster? 
In  what  state  is  sulphate  of  magnesia  often  detected  ? 


FLUORIDES.  279 

is  found  in  capillary  or  fibrous  crystals  at  Calatayud  in  Arragon, 
and  in  the  mines  of  Idria;  and  what  is  called  stalactitic  cobalt 
vitriol,  from  Herrengrund,  in  Hungary,  is  merely  sulphate  of 
magnesia,  tinted  red  by  oxide  of  cobalt. 

Polyhalite,  formerly  supposed  to  be  anhydrous  sulphate  of  lime, 
appears  from  the  analysis  of  Stromeyer  to  consist  of  the  sulphates 
of  lime,  magnesia  and  potash,  muriate  of  soda,  and  oxide  of  iron, 
in  a  state  of  chemical  combination,  though  the  muriate  and  oxide 
occur  in  very  small  proportions. 

149.  Sulphate  of  zinc  is  a  semi-transparent  saline  mineral,  of 
a  grayish  01  reddish-white  colour,  which  seems  to  be  produced 
from  the  decomposition  of  blende,  the  sulphuret  of  this  metal. 

Sulphate  of  iron,  copperas,  is  another  product  of  spontaneous 
decomposition,  being  derived  from  martial  pyrites,  and  appearing 
in  the  massive  form,  or  in  stalactitic  fibres,  yellow  scales,  or  red 
concretions. 

Sulphate  of  cobalt  is  a  soluble  saline  body,  of  a  pale  rose  or 
flesh  colour,  and  of  an  earthy  texture,  usually  in  the  stalactitic 
form,  found  in  the  Hartz  mines  and  elsewhere. 

Sulphate  of  copper  is  found  in  crystals  of  a  fine  blue  or  purple 
colour,  but  rarely  of  any  considerable  size  or  perfect  form. 

Sulphate  of  lead  occurs  crystallized  in  cuneiform  cctaedrons, 
variously  modified  or  aggregated,  imbedded  in  cellular  quartz, 
tinged  by  oxide  of  iron.  Translucent  crystals,  of  a  yellowish- 
gray  colour,  have  been  obtained  from  Parys  Mountain,  in  the  Isle 
of  Anglesea. 

150.  Sulphate  of  alumina  displays  some  variety  of  form  and 
composition.     Native   alum   is  found   crystallized,  fibrous,  and 
in  other  states,  in  various  places;  aluminite,  or  websterite,  is  a 
hydrated,  subsulphate  of  alumine,  mixed  with  sulphate  of  lime, 
resembling  pure  porcelain  earth,  found  on  the  coast  of  Sussex, 
near  Newhaven,  and  at  Halle,  in  the  territory  of  Magdebourg. 
Alumstone,  likewise  called   aluminite,  or  alunite,  occurring  in 
a  hill  at  Tolfa,  in  the  Pope's  dominions,  contains  potash  as  well 
as  sulphuric  acid  and  alumina ;  and  from  this  mineral  is  prepared 
Roman  alum.     Alumstone,  in  an  efflorescent  form,  is  met  with  in 
some  parts  of  the  U  nited  States. 

Fluorides. 

v!51.  The  fluor  minerals,  formerly  regarded  as  fluates  or  combi- 
nations of  an  acid  with  oxidated  bases,  have  been  ascertained  to 
consist  of  the  electro-negative  body  fluorine,  united  with  different 
metals. 

What  is  its  crystalline  form  ? 

What  is  the  composition  of  polyhalite  ? 

How  are  the  sulphates  of  zinc  and  iron  supposed  to  be  produced  ? 

How  does  sulphate  of  lead  crystallize  ? 


280  MINERALOGY. 

Fluor  spar,  erroneously  nam- 
ed  fluate  of  lime,  is  a  fluoride 
of  calcium,  found  in  several 
parts  of  the  world  and  exhi- 
biting various  forms  and  co- 
lours. It  occurs  compact,  fo- 
liated, crystallized,  granular, 
and  earthy  :  from  Chamouny 
are  obtained  rose-coloured 
crystals ;  from  Siberia,  a  vari- 
ety called  chlorophane,  which 
emits  a  brilliant  green  light  when  heated  ;  and  there  is  a  figured 
variety  called  fortification  fluor.  (See  marginal  figure.) 

Yttrocerite,  a  violet-coloured  mineral,  found  imbedded  in  quartz, 
at  Ytterby,  in  Sweden,  is  a  combination  of  the  fluorides  of  cal- 
cium, yttrium,  and  cerium. 

Fluate. 

152.  Cryolite,  is  a  mineral  found  in  "West  Greenland,  which 
derives  its  name  from  its  extreme  fusibility,  melting  like  ice:  it 
appears  from  the  analyses  of  Vauquelin  and  Berzelius,  to  be  a  com- 
pound of  fluoric  acid,  alumina,  and  soda.  It  is  of  a  colour  ap- 
proaching to  white,  translucent,  amorphous,  having  a  foliated 
fracture,  and  softer  than  fluor  spar. 

Chlorides. 

r  153.  The  chlorides  are  an  important  class  of  minerals,  the  na- 
ture of  which,  like  that  of  the  fluorides,  was  formerly  greatly  mis- 
apprehended. 

154.  Chloride  of  sodium,  long  known  to  chemists  by  the  appel- 
lation of  muriate  of  soda,  is  not  onty  found  most  abundantly  in  so- 
lution in  sea-water,  brine  springs  &c.,  but  also  occurs  in  vast  masses 
in  the  state  of  rock-salt,  at  Cordova  in  Spain,  Wieliczka  in  Poland, 
in  Hungary,  Siberia,  Africa,  arid  the  Andes  of  South  America,  and 
on  the  salt  bluffs  and  prairies  west  of  the  Mississippi.  It  crystal- 
lizes in  cubes  ;  and  among  its  varieties  are  the  fibrous,  red,  blue, 
and  violet,  and  the  stalactitical  rock-salt. 

Chloride  of  ammonium,  or  rather  muriate  of  ammonia,  native 
sal  ammoniac  is  found  chiefly  in  the  vicinity  of  volcanos. 

What  is  the  true  chemical  nature  of  fluor  spar  ? 

What  combination  of  substances  exist  in  yttrocerite  ? 

What  is  the  peculiarity  of  cryolite  ? 

What  is  its  chemical  nature  ? 

What  name  was  formerly  given  by  chemists  to  common  salt  ? 

What  is  now  its  chemical  designation  ? 

How  extensively  does  this  mineral  prevail  ? 

Where  is  chloride  of  ammonium  found  ? 


COAL.  281 

155.  Among  the  chlorides  of  lead  are  the  cotunnite,  from  Mount 
Vesuvius ;  the  basic  muriate  of  lead,  found  in  the  mines  of  Men- 
dip  ;    and  the  murio-carbonate  of  lead,  a  rare  mineral  found  in 
Derbyshire,  crystallized  in  square  prisms  terminated  by  pyramids, 
of  a  yellow  colour. 

Chloride  of  copper,  or  atacamite,  is  a  mineral  which  forms  beau- 
tiful groups  of  green  crystals,  found  in  Chili  and  Peru. 

156.  Chloride  of  silver,  called  corneous  silver,  or  horn  silver, 
from  its  appearance,  is  found  massive  and  crystallized  ;  in  colour 
and  form  resembling  gum  arabic  ;  or  of  a  pale-yellowish  green  or 
brown,  botryoidal,  lamellated,  earthy,  or  crystallized  in  minute 
cubes  and  octaedrons. 

Chloride  of  mercury,  which  has  the  same  homey  appearance, 
crystallizes  in  small  square  prisms,  terminated  by  flat  pyramids, 
and  otherwise  modified.  It  is  so  soft  as  to  be  sectile ;  and  it  be- 
comes volatilized  before  the  blowpipe. 

Organo -Chemical  Substances. 
Salts. 

157.  Mellate  of  alumina,  called  mellite,  or  honeystone,  from 
its  appearance,  is  found  in  small  amber-coloured  crystals,  in  beds 
of  brown  coal,  in  Thuringia. 

Oxalate  of  iron,  also  called  humboldtite,  was  formerly  considered 
as  resinous  iron  ore. 

Resins. 

158.  Amber  exhibits  numerous  varieties,  arising  from  various 
causes,  and  some  specimens  are  extremely  curious,  from  the  bodies 
imbedded  in  them.     It  occurs  in  rounded  pieces,  rough  on  the 
outside,  and  within  of  a  yellowish,  white,  or  reddish  colour;  and 
is  found  on  the  coast  of  Norfolk  in  England,  Prussia,  Mozam- 
bique in  Africa,  and  other  parts  of  the  world.     Some  specimens 
were  obtained  in  excavating  the  Chesapeake  and  Delaware  canal. 

Fossil  copal,  or  Highgate  resin,  a  substance  somewhat  resem- 
bling amber,  found  in  making  excavations  for  the  road  at  Highgate. 

Retinite,  or  retinasphalt,  a  mineral  from  Bovey,  in  Devonshire, 
of  a  yellow  and  reddish-brown  colour,  which  burns  with  a  fragrant 
odour. 

Bitumens. 

Varieties — Naphtha,  petroleum,  elaterite  or  elastic  bitumen, 
and  indurated  petroleum. 

What  is  the  common  designation  of  chloride  of  silver? 
What  is  the  difference  in  the  crystalline  forms  between  the  chloride  of 
mercury  and  that  of  silver  ?     Where  is  mellate  of  alumina  found  ? 
What  interesting  peculiarity  is  exhibited  by  amber? 
What  classification  of  substances  arises  from  their  modes  of  aggregation  ? 
2  A2 


282  MINERALOGY. 


Coal. 

160.  This  substance  presents  some  varieties,  more  interesting 
to  the  geologist  than  to  the  mineralogist ;  and  of  these  some  no- 
tices may  be  found  in  another  part  of  this  volume.* 

*  See  Oryctology. 


Works  in  the  Department  of  Mineralogy. 

Cleaveland's  Mineralogy.    2  vols.  8vo. 

Phillips's  Mineralogy. 

Ure's  Dictionary  of  Chemistry,  under  the  names  of  the  several 
minerals. 

Hauy  Traite  de  Mineralogie,  4  vols.  8vo.,  and  an  Atlas,  con- 
taining 120  plates  of  mineral  forms,  tables  of  characters  and 
angular  measures.  Though  the  system  of  Hauy  is  now  super- 
seded by  more  modern  arrangements,  his  work  is  often  found  of 
important  service  in  consequence  of  these  numerous  valuable  il- 
lustrations, which  aid  the  student  in  determining  a  mineral  by 
its  external  characters. 

Moh's  Treatise  on  Mineralogy,  translated  by  Haidinger.  3 
vols.  12mo. 

Del  Rio's  Elementos  de  Oryctognosia.  1  vol.  8vo.  Philad.  1833. 

Allan's  Manual  of  Mineralogy.  1  vol.  8vo.    Edinburgh.   1834. 


CRYSTALLOGRAPHY. 

1.  SOLID  bodies  appear  under  a  vast  variety  of  forms,  some 
depending-  on  organization,  and  others  on  molecular  attraction; 
the  latter  of  which   only  require  to  be  considered  at  present. 
These  forms  or  modes  of  aggregation  are  either  regular  or  irregu- 
lar; consisting  in  the  one  case  of  geometrical  solids,  variously 
modified;  and  in  the  other,  of  amorphous  solids,  or  those  which 
display  no  symmetrical  proportions. 

2.  Certain  figures,  arising  from  molecular  attraction,  are  termed 
crystals,  constituting  polyedral  solids,  terminated  by  surfaces, 
regular,  connected,  and  often  shining  with  a  lustre  equal  to  that 
of  a  polished  gem.     Few  objects  of  this  kind  are  more  beautiful 
than  frozen  water,  as  it  occurs  in  a  state  of  large  snow-flakes 
when  examined  by  a  microscope ;  or  as  it  may  be  observed  in  the 
hoar-frost,  incrusting  with  most  delicate  network  our  trees  and 
hedges,  or  formed  by  the  congelation  of  moisture  on  the  panes  of 
windows  in  a  cold  winter's  morning.* 

3.  'Those  bodies  which  are  capable  of  crystallization  have  been 
observed  to  affect  peculiar  forms  :    thus  rock-crystal  frequently 
occurs  beautifully  transparent  in  hexaedral  prisms,  terminated  by 
six-sided  pyramids ;  the  Derbyshire  fluor  spar  crystallizes  in  cubes, 
as  likewise  does  common  salt ;  alum,  or  sulphate  of  alumine,  forms 
octaedral  crystals;  and  sulphate  of  magnesia  tetraedral  prisms. 
These  forms,  however,  are  liable  to  modification  and  diversity 
from  different  causes,  as  will  be  subsequently  explained.  /Fluor 
spar  and  galena  sometimes  exhibit  octaedral  and  sometimes  cubic 
crystals  ;  and  carbonate  of  lime  appears  in  such  a  variety  of  forms 
that  it  is  difficult  to  decide  which  is  of  the  most  frequent  occur- 
rence.    *'Comte  de  Bournon,  in  his  elaborate  treatise  on  this 
mineral,  has  enumerated  fifty-six  modifications  ;  which,  differently 
combined,  furnished  him  with  above  six  hundred  varieties  of 
form."f 

4.  The  figures  of  crystals  may  be  conveniently  observed  by 
making  solutions  of  several  salts  in  water,  suffering  small  por- 
tions to  crystallize,  by  evaporation,  and   then  examining  them 
through  a  microscope.  \ 

What  is  meant  by  the  terra  crystal  ? 
How  is  the  process  of  crystallization  best  illustrated  ? 
What  important  leading  fact  constitutes  the  basis  of  this  science  ? 
What  deviations  from  uniformity  are  observed  in  crystals  of  the  same 
substance  ? 

How  may  the  figures  of  crystals  be  advantageously  studied  ? 


*  See  Treatise  on  Meteorology. 

t  Mrs.  Lowry's  Conversations  on  Mineralogy,  2d  edit.,  vol.  ii.  p.  26. 

283 


284 


CRYSTALLOGRAPHY. 


Mum. 


Common  Salt. 


Epsom  Salf. 


Take  a  dram  of  alum,  and  similar 
quantities  of  common  or  table  salt, 
epsom  salt,  glauber  salt,  nitre,  01 
any  other  soluble  saline  substances ; 
and  place  them,  separately,  in  clean 
wine-glasses,  or  gallipots,  then  pour 
on    each   parcel   rather  more   than 
enough  water  to  cover  it;  and  stir- 
ring   the    liquors   frequently,   after 
they  have  stood  half  an  hour,  let  a 
drop  of  each  fall  on  a  strip  of  clean  plate-glass, 
and  place  it  in  the  sun  or  on  the  chimney-piece, 
protected  from  the  dust,  so  that  the  water  may 
be  driven  off;  and  more  or  less  regular  crystals 
will  be  formed,  having  a  pleasing  appearance 
when  viewed  through  a  microscope.    The  mar- 
ginal figures  will  afford  some  idea  of  the  man- 
ner in  which  the  crystals  of  the  different  salts 
above  mentioned  are  grouped  and  constituted. 

5.  The  modifications  of  form  which  are  ob- 
served in  crystallized  bodies  are  sometimes 
owing  to  the  sudden  and  consequently  irregu- 
lar aggregation  of  the  crystalline  particles ; 
and  sometimes  the  presence  of  foreign  bodies 
may  accelerate,  interrupt,  or  very  materially 
interfere  with  the  process  of  crystallization. 
Hence  the  angles  or  edges  of  crystals  may  be 
truncated  or  rounded ;  and  cylinders,  spheri- 
cal, lenticular,  or  agglomerated  masses  may 
be  produced,  bearing  but  a  faint  resemblance 
to  the  proper  form  of  the  salt. 

6.  In  order  to  obtain  regular,  large  and  well- 
shaped  crystals  of  any  salt,  a  saturated  so- 
lution  should   be   made   in   distilled   water, 
and  set  by  in  a  moderately  warm  situation, 
where  it  may  remain  undisturbed,  so  that  the 
fluid  may  evaporate  slowly;    and  a  gradual 
deposition  of  the   saline  particles  will  then 
take  place,  yielding  symmetrical  crystals  of  a 
larger  size  than  can  be  produced  by  any  other 
management. 

7.  The   interesting  appearance  of  certain 
crystals   and    their  relative   permanence   of 

form,  amidst  a  seeming  variety,  drew  forth  some  striking  observa- 
tions from  Dr.  Freind,  in  his  lectures  on  chemistry  at  Oxford,  in 
the  early  part  of  the  last  century. 

8.  "  The  beauty  and  variety  of  the  figures  of  crystals  is  so 

To  what  are  modifications  of  crystalline  forms  supposed  to  be  due  ? 
How  are  the  perfect  crystals  of  a  salt  to  be  obtained  ? 


Glauber  Salt. 


ISOMORPHISM.  285 

admirable,  that  there  is  scarcely  any  thing  in  nature  which  can 
entertain  the  eye  more  agreeably.  These  figures  are  sometimes 
eeen  by  the  naked  eye,  but  by  the  help  of  microscopes  are  dis- 
cerned much  better.  In  common  salt  we  plainly  discover  quadri- 
lateral pyramids,  with  square  bases  ;  in  sugar,  the  same  pyramids, 
Nitre.  with  oblong  and  rectangular  bases.  The 

crystals  of  vitriols  very  much  resemble  ici- 
cles, united  one  to  another  with  great  va- 
riety; among  which  lie  some  polygons, 
as  may  be  discovered  by  the  naked  eye. 
Sal  ammoniac  very  elegantly  imitates  the 
branches  of  a  tree ;  and  salt  of  hartshorn 
(carbonate  of  ammonia)  looks  like  a  qui- 
ver of  arrows."  Glauber's  sal  mirabilis, 
which  is  made  of  common  salt  and  vi- 
triol, (sulphate  of  soda,)  exhibits  the  figure  of  both  salts. 
Nitre  appears  in  certain  prismatical  columns,  not  much  un- 
like bundles  of  sticks;  among  which  there  are  interspersed 
some  rhomboids*  and  some  pentagons,  which  seem  to  come 
very  near  those  of  common  salt.  Hence  Lemery  has  justly 
remarked,  that  nitre  could  not  be  purified  by  any  art  or  contrivance 
whatever;  but  something  of  a  sal  gem,  01  fossil  salt,  would  stick 
to  it.  But  salt  of  tin  outdoes  all  for  beauty,  in  which  are  lines 
like  little  needles,  which  spread  themselves  every  where  from  a 
point,  as  from  a  centre,  so  as  to  represent  a  star,  much  like  what 
we  see  in  the  regulus  of  Mars,  (metallic  iron.)"f 

9.  Dr.  Freind  proceeds  to  remark,  that  it  is  a  circumstance  "  very 
peculiar  in  these  salts,  that  let  them  be  never  so  divided,  and  re- 
duced into  minute  particles,  yet  when  they  are  formed  into  crys- 
tals, they  each  of  them  reassume  their  proper  shape ;  so  that  one 
might  as  easily  divest  and  deprive  them  of  their  saltness  as  of 
their  figure."    The  intimate  relation  between  crystalline  form  and 
chemical  composition,  which  attracted  the  attention  of  this  inge- 
nious writer,  has  been  extensively  investigated  by  more  recent 
inquirers. 

10.  Among  the  facts  wThich  have  been  disclosed  in  consequence 
of  their 'researches,  one  of  the  most  singular  and  important  is,  that 
bodies,  both  simple  and  compound,  which  are  capable  of  crystal- 
lization, appear   to  form  groups  characterized   by  similarity  of 
structure  ;  so  that  one  group  may  include  several  substances,  all 
crystallizing  in  similar  square  prisms,  another  group  consists  of 

What  observatious  on  crystalline  forms  were  made  by  Dr.  Freind  ? 
What  did  Lemery  remark  in  respect  to  nitre  ? 

What  important  facts  in  regard  to  similarity  of  structure  have  been  dis- 
closed by  modern  mineralogists  ? 

*  Nitre  sometimes  consists  partly  of  nitrate  of  soda,  which  forms  rhom- 
boidal  crystals ;  but  nitrate  of  potash,  when  quite  pure,  crystallizes  in 
hexaedral  prisms,  generally  with  diedral  summits. 

t  Chymical  Lectures,  by  John  Freind,  M.D.,  1712,  pp.  144—146. 


286  CRYSTALLOGRAPHY. 

bodies  forming  similar  octaedral  crystals,  and  various  others,  the 
members  of  which  respectively  are  distinguished  by  peculiar 
figures.  As  an  example  of  such  a  group  of  minerals  may  be  men- 
tioned calc  spar,  (Iceland  crystal,)  bitter  spar,  carbonate  of  mag- 
nesia and  iron,  carbonate  of  iron,  manganese  spar,  zinc  spar,  and 
magnesia  spar,  all  crystallizing  in  rhomboedrons.  The  discovery 
of  this  disposition  among  mineral  bodies  differently  constituted  to 
assume  a  common  form,  led  to  the  assumption  of  the  doctrine 
of  isomorphism,  already  alluded  to  in  the  Treatise  on  Chemistry.* 
The  law  of  isomorphism,  as  announced  by  Mitscherlich,  in  its  ut- 
most generality  is  as  follows  :  "'The  same  number  of  atoms  com- 
bined in  the  same  way  produces  the  same  crystalline  form  ;  and 
the  same  crystalline  form  is  independent  of  the  chemical  nature 
of  the  atoms,  and  is  determined  only  by  their  number  and  relative 
position."! 

11.  A  few  observations  may  be  added  to  explain  in  some  de- 
gree the  general  principle  on  which  depends  the  association  of 
isomorphic  substances.     An  examination  of  the  group  of  rhom- 
boedral  minerals  mentioned  above,  will  demonstrate  amidst  diver- 
sity of  composition  a  similarity  of  atomic  constitution.    All  those 
bodies  of  which  crystallized  carbonate  of  lime,  or  calc  spar,  may 
be  regarded  as  the  isomorphic  type,  appear  to  correspond  in  the 
number  of  their  atoms  with  that  body  :  thus, 

Calc  spar  consists  of  1  carb.  acid  -f-  1  lime 

Bitter  spar  ....  1  carb.  acid-f-  1  lime-f- 1  carb.  acid  +  1 
magnesia. 

Carbonate  of  magnesia  and  iron  consists  of  1  carb.  acid  -\-  I  mag- 
nesia -j-  1  carb.  acid-|-  1  oxide  of  iron. 

Carbonate  of  iron 1  carb.  acid  +  1  oxide 

of  iron. 

Manganese  spar 1  carb.  acid  +  1  oxide 

of  manganese. 

Zinc  spar 1  carb.  acid  -f-  1  oxide 

of  zinc. 

Magnesia  spar 1  carb.  acid-f- 1  mag- 
nesia. 

12.  In  all  the  simple  carbonates  of  the  preceding-  group,  one 
atom  of  carbonic  acid  is  combined  with  one  atom  of  a  metallic  pro- 
toxide ;  and  in  the  compound  carbonates  the  atomic  quantities  are 

What  examples  can  be  given  of  minerals  thus  resembling  each  other  in 
form  though  differing  in  constitution? 

What  law  of  isomorphism  is  applicable  to  these  cases? 
Illustrate  this  in  the  case  of  mineral  carbonates. 


*  See  p.  123,  note. 

t  Rep.  of  Brit.  Assoc.  for  1832,  p.  422.    For  a  list  of  isomorphic  bodies 
by  Prof.  Miller,  see  the  same  volume. 


ISOMORPHISM,  &C.  287 

are  doubled.  The  same  correspondence  of  atomic  constitution 
seems  to  prevail  in  groups  of  more  complicated  chemical  combi- 
nation^ :  thus  tremolite  and  anthophyllite  are  double  silicates, 
the  composition  of  which  is  as  follows : 

Tremolite  consists  of  1  lime+  1  silica  +  3  magnesia +  2  silica. 
Anthophyllite     .     .     1  oxide  of  iron  -f-  1  silica  -f-  3  magnesia  -j-  2 
silica. 

13.  Hence  it  appears  that  the  only  difference  between  these 
Dodies  consists  in  the  former  containing  one  atom  of  lime,  (pro- 
toxide of  calcimn,)  and  the  latter  one  atom  of  protoxide  of  iron  ;  and 
they  both  crystallize  in  oblique  prisms.    In  numerous  other  cases 
it  has  been   found,  that   one   oxide   or  acid,   having   the   same 
atomic  constitution   with  another  oxide  or  acid,  may  replace  it, 
or  be  substituted  for  it  in  the  composition  of  minerals,  giving  rise 
to  similar  crystalline  forms  ;  and  thus  groups  are  produced,  each 
composed  of  two  or  more  bodies  corresponding  in  the  numbers  of 
their  atoms,  and  in  crystalline  form. 

14.  There  is  an  inferior  degree  of  analogy  of  form  observable 
among  minerals,  which  probably  arises,  as  in  the  cases  already 
noticed,  from  the  atomic  constitution  of  bodies.     Certain  crystal- 
line compounds  are  found  to  differ  among  themselves  merely  in 
the  angular  measurements  of  their  crystals.   Thus  sulphate  of  ba- 
rytes, sulphate  of  lead,  carbonate  of  lead,  and  some  others,  form 
right  rhombic  prisms  ;  but  the  obtuse  angles  of  the  rhombic  prism 
of  sulphate  of  barytes  measure  101°  42';  those  of  sulphate  of 
lead  103°  42';  and  those  of  carbonate  of  lead  117°  18'.*    Hence 
groups  of  bodies  thus  related  are  said  to  be  ple&iomorphous  ;-j-  and 
the  term  fwmoiomorpkous^  1ms  been  adopted  to  distinguish  groups 
of  crystalline  substances  differing  more  widely  in  their  angles. 

15.  It  has  also  been  remarked,  that  while  differently  constituted 
compounds  may  agree  in  crystalline  form,  there  are  bodies,  both 
simple  and  compound,  which  are  capable  of  existing  under  two 
forms,  which  are  incompatible  or  not  derivable  from  one  common 

How  is  the  composition  of  compound  carbonates  seen  to  be  analogous  to 
that  of  simple  ones  ? 

How  is  tremolite  shown  to  be  isomorphic  with  anthophyllite  ? 

What  substitution  of  an  ingredient  is  often  found  consistent  with  the 
preservation  of  a  crystalline  form  ? 

In  what  circumstances  are  crystals,  otherwise  similar,  found  to  vary  from 
each  other  ? 

What  is  the  measure  of  the  obtuse  angles  of  sulphate  of  barytes  ? — ol 
lead  ?  What  of  the  carbonate  of  lead  ? 

What  term  expresses  the  relation  of  crystals  of  which  the  angles  are 
nearly  the  same  ? 

What  term  applies  to  those  which  having  forms  generally  alike  differ 
greatly  in  the  angles  ? 

*  Report  of  the  British  Association  for  1832,  p.  428. 

t  From  the  Greek  IIA^fftoj,  nearly  alike,  and  Mop^ybrm. 

t  From  the  Greek  "G^ony,  similar,  and  M0p£>>. 


288  CRYSTALLOGRAPHY. 

| 

form.  Sulphur  is  found  crystallized  in  octaedrons  with  rhombic 
bases,  and  also  in  rhombic  prisms.  Pure  carbon  occurs  in  nature 
in  two  states,  constituting  the  diamond  and  graphite;  the  former 
exhibiting  regular  octaedral  crystals,  and  the  latter  crystallizing  in 
hexaedral  plates,  striated  parallel  to  some  of  their  sides.  Sulphur 
and  carbon  thus  display  a  duplicity  of  form,  a  property  in  these 
and  other  bodies  denoted  by  the  term  dimorphism.* 

16.  The  phenomena  of  plesiomorphism,  homoiomorphism,  and 
dimorphism,  which  have  all  an  obvious  relation  to  isomorphism, 
indicate  the  necessity  of  further  researches  to  elucidate  the  nature 
and  causes  of  these  appearances,  which  may  probably  lead  to 
very  curious  and  interesting  discoveries. 

17.  The  modifications  and  seeming  anomalies  of  form  which 
often  occur  in  crystallized  bodies  take  place  under  certain  laws ; 
the  deviation  from  the  usual  figure  of  the  crystal  depending  on 
addition  or  subtraction  of  parts  necessary  to  make  up  the  regular 
solid,  or  primary  form  of  a  mineral,  in  any  given  case.    -That  the 
varieties  of  form  in  crystals  of  the  same  mineral  may  be  referred 
to  truncations  of  an  invariable  primary  nucleus,  was  an  opinion 
that  appears  to  have  been  started  by  the  French   mineralogist, 
Rome   de  Lisle ;  the  idea  also  occured  to    Gahn,  professor   of 
mineralogy  at  Upsal,  who  having  broken  a  piece  of  the  dogtooth 
calcareous  spar,  observed  that  it  was  throughout  composed  of 
rhomboidal  crystals  ;  and  hence  Professor  Bergmann  was  led  to 
conjecture   that   in   all   crystallized   bodies  there  must  exist   a 
primary  nucleus. 

18.  The  inquiry  was  then  taken  up  by  the  Abbe  Haiiy,  who  is 
said  to  have  had  his  attention  drawn  to  it  by  an  accident  in  itself 
somewhat  awkward  and  perplexing.     A  person  of  fortune  who 
had  collected  a  cabinet  of  minerals  as  expensive  curiosities,  was 
showing  them  to  M.  Haiiy ;  and,  handing  to  him  one  very  beau- 
tiful crystalline  specimen  that  he  might  inspect  it  more  readily, 
the  stone  slipped  from  the  hand  of  the  visiter,  and  falling  on 
a  marble  pavement,  was  split  in  several  pieces,  which  the  owner 
regarding  as  worthless,  while  courteously  accepting  the  apologies 
of  the  chagrined  philosopher,  ordered  a  servant  to  take  up  and 
throw  away.     M.  Haiiy  struck  with  the  brilliance  of  the  smooth 
surfaces  of  the  fractured  parts   begged  to  be  allowed  to  inspect 
them,  and  took  them  home  to  examine  the  structure  of  the  mineral 
more  at  leisure.     He  found  that  it  was  susceptible  of  cleavage 
only  in  particular  directions,  and  to  a  certain  extent ;  and  having 
made  corresponding  observations  on  other  crystallized  substances, 
he  was  at  length  enabled  to  reduce  to  a  regular  system  the  laws 

To  what  is  the  term  dimorphism  applied  ? 

By  whom  was  the  idea  of  primitive  crystalline  forms  first  advanced  ? 
What  circumstance  is  said  to  have  led  Haiiy  to  the  investigation  of 
primitive  nuclei? 
On  what  plan  did  he  proceed  to  form  his  system  of  mineralogy  ? 

*  From  the  Greek  At  j,  twice,  (in  comp.  a  omitted,)  and  Mop0^. 


PRIMITIVE  FORMS  OF  CRYSTALS.  289 

of  crystallization,  with  reference  to  the  manner  in  which  crystals 
are  deduced  in  their  several  varieties  from  a  primitive  nucleus. 
19.  The  relations  between  the  different  modifications  of  form  in 
a  mineral  may  be  exemplified  by  taking  a  crystal  of  the  fluor  spar 
in  one  of  the  simplest  of  its  natural  forms,  the  cube,  exhibited  in 
No.  1.         ^6  margin.    Now  it  will  be  found  on  trial  that  the 
solid  angles,  A,  B,  C,  D,  &c.,  may  all  be  removed 
by  a  knife  with  proper  pressure,  and  thus  the  eight 
angles  may  be  replaced  by  brilliant,  flat,  triangular 
surfaces,  as  in  the  next  marginal  figure,  No.  2.  The 
solid  will  then  consist  of  fourteen  sides  instead  of 
No.  2.       six ;  and  each  of  the  triangular  sides  may  be  enlarged  at 
the   expense  of  the  square  sides,  by  continuing  the 
cleavage  of  increasing  triangular  planes,  so  as  to  form* 
the  succeeding  figure,  No.  3. 

20.  At  length,  pursuing  the  separation  of  the  crystal 
strata  in  the  same  direction,  will  be  produced  the  re- 
maining figures,  Nos.  4  and  5,  in  the  last  of  which  no 
part  of  the  original  cube  remains,  every  angle  having 
been  cut  away  so  as  to  form  eight  new  faces,  consti- 
tuting an  octaedron,  which  is  the  primary  form  of  the 
fluor  spar. 

21.  A  crystal  of  common  salt,  exhibiting  the  same 
No.  4.   cubic  form  with  the  fluor  spar,  differs  from  it  in  structure, 

for  its  angles  cannot  be  separated  so  as  to  leave  a  smooth 
surface ;  and  the  crystal  will  admit  of  cleavage  or  sub- 
division  only  in  layers  parallel  to  either  or  all  its  sides ; 
No.  5.  so  that  a  large  cube  can  be  separated  into  a  number  of 
small  ones,  but  not  reduced  by  cleavage  to  any  other  form  ; 
hence  the  cube  is  the  primitive  form  or  nucleus  of  the 
crystal  of  common  or  sea  salt.  In  the  same  manner,  pon- 
derous spar,  or  sulphate  of  barytes,  can  be  divided  with  regu- 
larity only  so  as  to  form  right  rhombic  prisms  ;  and  selenite,  sul- 
phate of  lime,  into  right  prisms :  these  therefore  are  the  nuclei, 
or  primitive  forms  of  their  respective  crystals. 

22.  As  the  primitive  nuclei  of  crystals  may  be  developed  by 
dissection,  so  it  may  be  ingeniously  shown  how  the  varieties  of 
crystals  may  be  derived  from  the  superposition  of  lamina  on 
parallel  surfaces,  diminishing  regularly  in  extent,  so  as  at 
length  to  form  the  summit  of  a  solid  angle,  or- the  edge  of  a  line 
joining  two  angles.  It  is  in  this  manner  that  Hatiy,  attributing  to 
every  crystallizable  substance  a  primitive  or  simple  form,  ascer- 
tained by  division  as  before  stated,  or  else  inferred  from  a  compari- 

In  what  manner  may  the  cube  of  fluor  spar  be  first  varied  by  cleavage  ? 

To  what  form  will  it  be  ultimately  brought  ? 

How  does  the  crystal  of  chloride  of  sodium  differ  from  that  of  fluoride 
of  calcium  in  regard  to  the  cleavage  of  its  angles  ? 

To  what  primitive  form  is  the  crystal  of  ponderous  spar  capable  of  being 
reduced  ?  To  whom  is  the  doctrine  of  increments  and  decrements  in  crys- 
tals to  be  ascribed  ? 

2B 


290  CRYSTALLOGRAPHY. 

son  with  others  already  known,  proceeds  to  derive,  from  his  doc- 
trine of  increments  and  decrements,  the  various  secondary  forms 
that  may  be  observed  in  different  specimens  of  any  given  mineral. 

23.  According  to  the  system  of  Hauy,  all  crystals  are  derived 
from  five  or  six  primitive  forms.  These  are,  (1.)  the  parallelopiped, 
including  the  cube,  rhomboid,  and  all  their  varieties;   (2.)  the 
tetraedron;  (3.)  the  octaedron ;  (4.)  the  hexaedral  prism;  (5.) 
the  rhomboidal  dodecaedron  ;  to  which  may  be  added,  (6.)  the 
dodecaedron,  with  isosceles  triangular  faces. 

24.  All    solids   having  six  sides,  whose  respective  bounding, 
lines  taken  in  pairs  are  parallel  with  each  other,  and  the  opposite 
sides  also  equal  and  parallel,  forming  so  many  parallelograms,  are 
termed  parallelepipeds.     Such  an  arrangement  of  surfaces  must 

Obviously  admit  of  some  variety ;  and  thus  it  maybe  perceived 
that  the  parallelopiped  will  include  the  cube,  the  square  prism,  the 
rhomboid,  the  right  rhombic  prism,  and  the  oblique  rhombic 
prism. 

/]      25.  The   cube,   as  appears   in   the  margin,   has   six 

square  sides,  all  equal,  like  common  dice ;  it's  proportions 

being  invariable.  ' 


2G.  When  a  body  is  terminated  by  four  equal  oblong 
parallelograms  laterally,  and  two  square  parallelograms  at 
the  ends,  it  is  called  a  square  prism. 

27.  The  rhomboid  has  its  opposite  sides  equal  and 
parallel,  but  none  of  them  are  square,  each  having  two 
obtuse  and  two  acute  angles,  instead  of  four  right  an- 
gles, like  the  cube. 

28.  There  are  many  varieties  of  rhomboids  characterized  by 
the  relative  diversities  of  their  corresponding  angles  ;  some 
rhomboids  differing  so  little  from  the  perfect  cube  that 
their  real  nature  can  only  be  ascertained  by  the  measure- 
ment of  their  angles,  others  bearing   but   a  very  distant 
resemblance  to  it,  as  in  the  marginal  figure,  representing 
a  very  oblique  rhomboid. 

29.  The  right  rhombic  prism  bears  the  same  relation  to 
the  square  prism  that  the  rhomboid  does  to  the  cube.    In 
the    square  prism  the  angles  are  all  equal,  and  are  right 
angles ;  but  in  the  right  rhombic  prism  the  sides  or  lateral 
planes  meet  alternately  at  angles  greater  or  less  than  90 

degrees ;  but  the  terminal  planes,  or  those  at  the  extremities  of 
the  prism,  form  by  their  junction  right  angles. 

To  how  many  and  what  simple  forms  did  Hairy  reduce  all  crystals  ? 

What  is  a  parallelopiped  ? 

How  many  varieties  does  it  admit? 

How  does  the  rhomboid  differ  from  the  cube? 

What  is  an  oblique  rhomboid? 

How  is  the  right  rhombic  prism  formed  ? 


PRIMITIVE   FORMS  OF  CRYSTALS.  291 

30.  The  oblique  rhombic  prism  differs  from  the  preceding 
figure  in  the  position  of  its  terminal  planes,  which  do  not 
form  right  angles  with  the  lateral  planes,  but  are  placed 
obliquely,  so  that  the  terminal  and  lateral  planes  meet  at 
obtuse  and  acute  angles  alternately. 

31.  The  tetraedron  is  the  simplest  of  all  regular  figures 

A  having  plane  surfaces.  It  is  a  solid,  included  within  four 
triangular  planes,  equal  and  similar,  each  of  the  three 
sides  being  of  the  same  dimensions. 

Some  notice  has  been  already  taken  of  the  octaedron,  as  the 
figure  produced  by  the  truncation  of  the  solid  angles  of  a  cube. 
There  are  varieties,  however,  of  this  figure,  arising  from  those  of 
the  eight  planes,  by  which  it  is  terminated. 

,4x  32.  The  regular  octaedron  has  all  its  planes  equal  and 

^-\-~^\  similar  triangles,  each  of  their  three  sides  being  of  the 

\A  /  same  length.     All  lines  drawn  through  its  centre  from 

^/^     either  angle  to  that  opposite  to  it  will  be  of  equal  length, 

or  in  other  words  it  has  three  equal  axes.     This,  however,  is  not 

the  case  with  all  octaedrons,  some  having  one  axis  longer  and 

some  shorter  than  the  other  two. 

^r.  33.  The  obtuse  octaedron  differs  from  the  former  in 

y^      ^-xhaving  tne  ^ne  which  forms  the  base  of  its  triangular 

^\7*r — ~~/  sides  longer  than  those  which  meet  at  the  apex,  so 

^^\/         that  what  may  be  termed  its  principal  axis  is  shorter 

than  its  other  axes. 

»         34.  The  acute  octaedron  will  be  perceived  at  once  to  be 

n\   exactly  the   reverse  of  the  foregoing,  its  base  line  being 

//  \  shorter  than  those  which  form  the  apex,  and  its  principal, 

Vf/  axis  longer  than  the  others.  These  forms  will  obviously  ad- 

W   mil  of\  several  modifications,  the  nature  of  which  may  be 

*     comprehended  without  difficulty  from  what  has  been  already 

stated.    •   • 

O35.  The   hexaedral  prism   derives  its  name  from  the 
number  of  its  sides,  which  are  similar  parallelograms, 
not  square,  but  oblong.   They  are  six  in  number,  and  are 
called  lateral  planes,  and  as  they  meet  the  terminal  planes, 
the  latter  are  hexaedral  and  hexagonal ;  that  is,  they  have  six  edges 
and  six  angles.    The  terminal  planes  are  parallel  with  each  other. 
-  36.  The  rhomboidal  dodecaedron,  as  its  name  implies, 

\**\  has  twelve  sides.  These  are  all  of  similar  form,  each 
>plane  being  a  rhomb,  of  which  the  four  bounding  lines 
are  of  the  same  length,  and  the  opposite  lines  are  parallel, 
forming  two  acute  and  two  obtuse  angles  in  each  plane. 

How  is  the  oblique  rhombic  prism  formed? 

What  peculiar  character  does  the  tetraedron  possess  compared  with  other 
figures  ?     What  is  a  regular  octaedron  ? — an  obtuse  octaedron  ? 
How  does  the  acule  differ  from  the  two  other  forms  of  octaedron? 
How  many  sorts  of  planes  belong  to  prisms? 

What  are  the  plane  figures  constituting  the  bases  of  hexaedral  prisms? 
What  is  the  plane  figure  of  each  side  in  the  rhomboidal  dodecaedron  ? 


292 


CRYSTALLOGRAPHY. 


This  figure  is  susceptible  of  numerous  modifications,  by  tbe  trunca- 
tion of  edges  or  angles. 

37.  The  dodecaedron  with  isosceles  triangular  faces  is  a 
figure  having  twelve  equal  triangular  sides,  differing 
from  the  octaedron  in  the  number  of  its  sides,  and  like 
that  figure,  admitting  of  modifications,  according  to  the 
length  of  its  principal  axis. 

38.  The  connexion  of  one  form  with  another,  or  the 
transition  from  one  to  another,  has  been  exemplified  in  the  deduc- 
tion of  the  octaedron  from  the  cubic  crystal  of  fluor  spar.     (See 
p.  289.)    The  following  figures  will  serve  in  like  manner  to  show 
what  modifications  are  produced  by  the  truncation  of  the  angles 
and  edges  of  an  octaedron  : 

A  B  C 


39.  In  fig.  A,  the  angles  only  of  the  octaedron  are  truncated,  in 
fig.  B,  the  edges  only,  and  in  fig.  C,  both  the  angles  and  the  edges. 
If  we  suppose  the  division  of  an  octaedral  crystal  to  be  continued 
in  the  direction  of  the  planes  formed  by  the  truncation  of  the 
edges,  fig.  B,  in  which   the  triangular  planes  of  the  truncated 
octaedron  are  separated  from  each  other  by  narrow  hexangular 
planes,  a  modification  will  be  produced,  exhibiting  an  increase  of 
the  hexangular  planes,  and  reduction  of  the  triangular  ones,  each 
however  retaining  its  characteristic  shape. 

40.  By  pursuing  the  division  in  the  same  direction,  the  original 
planes  may  be  entirely  removed,  the  triangular  faces  disappearing, 
and  the  hexangular  ones  being  changed  into  rhomboedral  surfaces. 
Such  a  series  of  modifications  may  be  observed  in  the  fluor  spar, 
and  more  commonly  in  the  red  oxide  of  copper,  serving  to  show 
how  the  rhomboedral  dodecaedron  may  result  from  the  replace- 
ment of  the  edges  of  the   octaedron.     But  in  neither  of  these 
minerals  can  the  rhomboedral  dodecaedron  be  obtained  by  cleavage 
from  the  truncated  octaedron ;  for  the  laminae  of  the  crystal  of  fluor, 
or  red  oxide  of  copper,  admit  of  separation   only  in    directions 
parallel  with  the  planes  of  the  octaedron,  that  being  the  primitive 
form  or  nucleus  of  the  crystals  of  the  mineral  in  question. 

41.  In  this  transition  from  one  form  to  another  in  the  construction 
of  crystals,  it  seems  as  if  nature  in  the  generation  of  each  crystal 
assumed  a  central  nucleus*  regular  and  constant  in  each  species 

IP  what  three  modes  may  the  simple  octaedron  be  varied  by  truncation  ? 

To  what  form  would  continued  cleavage  along  the  edges  only  eventu- 
ally lead  ? 

In  what  minerals  do  we  find  a  form  similar  to  what  this  process  would 
produce  ? 


LAW  OF  DECREMENTS.  »      293 

respectively,  and  on  the  several  faces  of  that  nucleus  applied  suc- 
cessive laminae,  all  parallel  and  similar  to  each  other,  but  diminish- 
ing regularly  in  extent,  so  as  at  length  to  terminate  in  a  point 
forming  the  summit  of  a  solid  angle,  or  in  a  line  forming  the  edge 
of  the  new  crystal. 

42.  Thus  from  a  cubic  nucleus,  the  formation  of  a  rhomboidal 
dodecaedron  may  be  supposed  to  take  place,  by  the  addition  of 
successive  laminae  on  each  face  of  the  cube,  which  having  a  height 
denoted  by  1,  decrease  gradually  on  their  borders  by  a  quantity 
also  denoted  by  1.     So  likewise  a  solid  of  twenty-four  faces  may 
be  conceived   to  be  formed  from  a  cube  by  the   application  of 
laminae,  the  thickness  of  which  is  denoted  by  1,  and  the  successive 
lateral  decrements  by  2,  by  3,  or  any  higher  number,  according  as 
the  pyramid  is  more  or  less  elevated  or  depressed. 

43.  An  octaedron  may  in  like  manner  be  formed  from  a  cubic 
nucleus  by  the  successive  application  of  laminae  having  angular 
decrements ;  and  by  irregular,  intermediate,  or  combined  decre- 
ments, a  vast  variety  of  secondary  forms  may  be  produced  from  a 
very  limited  number  of  primitive  nuclei.    Hence  in  general,  when 
the  form  of  the  nucleus  of  a  mineral  has  been  ascertained,  nothing, 
is  more  easy  than  to  determine  in  what  manner  laminae  must  be 
applied,  and  the  law  according  to  which  they  ought  to  decrease, 
in  order  to  produce  any  given  form  of  a  crystal,  the  angles  of 
which  have  been  previously  measured. 

44.  "  But  however  ingenious  this  method  of  accounting  for  the 
diversity  of  crystals  of  the  same  substance  may  appear,  and  im- 
portant as  were  the  discoveries  of  the  learned  author,  it  must  be 
admitted  that  it  can  only  be  regarded  as  an  hypothesis  which  may 
assist  us  in  our  researches.     Indeed  it  is  not  probable  that  nature 
should  commence  by  the  formation  of  the  primitive  crystal,  in  order 
to  apply  to  it  decremental  laminae.  The  bare  inspection  of  crystals, 
which  are  often  exceedingly  small,  and  yet  highly  complicated, 
appears,  on  the  contrary,  to  announce  that  all  the  forms  have  been 
produced  by  a  single  effort,  (prodnites  d'un  seuljet  ,•)  while  on  the 
other  hand,  it  may  be  observed  that  the  large  crystals  are  only 
regular  assemblages  of  very  small  ones,  often  similar  to  the  large 
crystals  which  they  form,  and  sometimes  different  from  them."* 

45.  "  These  observations  prove  clearly,  that,  in  general,  crystalli- 
zation does  not  take  place  in  nature  according  to  the  supposition 
adopted  in  the  theory  which  has  been  given,  but  that  the  different 
crystals  result  rather  from  the  sudden  arrangement  of  the  regular 
molecules  among  themselves,  in  the  act  of  spontaneous  solidifica- 
tion. For  in  studying  the  manner  in  which  certain  particles  infi- 

How  may  a  rhomboidal  dodecaedron  be  conceived  to  result  from  a  cubic 
nucleus  ? 

How  may  the  solid  of  twenty-four  faces  be  derived  from  the  same  origi- 
nal form  ? 

To  what  objection  is  the  theory  of  Haiiy  shown  to  be  liable? 


*  Beudant  Traite  Element,  de  Physique,  p.  85. 
2u2 


294       *  CRYSTALLOGRAPHY. 

nitely  [indefinitely]  minute,  of  a  determinate  form,  may  combine 
together,  according  to  the  number  and  the  position  of  their  faces, 
we  may  be  led  to  conclude  that  the  different  polyedral  figures  to 
which  they  give  rise  depend  on  the  number  in  which  they  are  at- 
tracted together  at  the  moment  of  crystallization.  Thus,  for 
example,  it  may  be  comprehended  that  cubic  particles  can  only 
form  complete  cubes  in  those  cases  in  which  these  molecules  unite 
together  in  cubic  numbers,  as  8,  27,  64,  125,  &c. 

46.  With  a  little  attention,  we  perceive,  likewise,  that  regular 
octaedrons  can  only  be  formed  when  cubic  molecules  combine  in 
one  of  the  numbers  of  the  series  7,  25,  63,  129,  &c.     Further, 
dodecaedrons  with  rhombic  planes  will   be  produced  when  the 
molecules  are  attracted  together,  in  one  of  the  numbers  of  the  series 
33,  185,  555,  &c."* 

47.  These  speculations  might  be  pursued  further,  and  it  might  be 
shown  how  other  forms  might  be  derived  from  cubic  particles  ;  but 
some  figures  would  require  for  their  production  very  extensive  and 
complicated  series  of  numbers  of  molecules  ;  and  hence  this  theory 
is  objectionable,  as  wanting  that  simplicity  usually  observable  in 
the  laws  of  nature.     There  is  more  probability  in  the  hypothesis 
ingeniously   proposed    by   Dr.  Wollaston,   who   considered   the 
primitive  particles  as  spheres,  which,  by  mutual  attraction,  assume 
that  arrangement  which  brings  them  as  near  as  possible  to  each 
other. 

48.  When  a  number  of  similar  balls  are  pressed  together  in  the 
same  plane,  they  form  an  equilateral  triangle ;  and  if,  when  thus 
arranged,  they  were  cemented  together,  and  the  mass  afterwards 
broken  asunder,  the  lines  in  which  separation  would  most  readily 
take  place,  would  form  with  each  other  angles  of  60  degrees.     A 
single  ball  placed  any  where  upon  such  a  stratum  would  touch 
three  of  the  lower  balls,  and  planes  parallel  to  the  sides  of  the 
figure  thus  formed  would  include  a  regular  tetraedron.     A  square 
of  four  balls,  with  a  single  ball  on  the  centre  of  each  surface  would 
constitute  an  octaedron ;  and  on  applying  two  other  balls  at  op- 
posite sides  of  the  octaedron,  the  group  would  represent  an  acute 
rhomboid.     The  construction  of  the  numerous  varieties  of  figures 
which  occur  among  crystals  might  be  readily  explained,  by  ad- 
mitting the  existence  of  oblate  and  oblong  spheroidal  molecules, 
as  well  as  those  of  a  globular  figure. f 

49.  Crystals  may  not  only  differ  one  from  another,  as  a  rhombic 
prism  from  an  octaedron  or  a  dodecaedron,  but  one  rhombic  prism 
may  differ  from  another;  for,  since  the  rhomb  is  characterized  by 
having  one  of  its  adjacent  angles  smaller  than  a  right  angle  and 

To  what  circumstance  may  \ve  attribute  the  different  forms  of  crystals 
supposing  the  ultimate  particles  all  alike  ? 

What  hypothesis  did  Dr.  Wollaston  propose  for  the  solution  of  the  ques- 
tion respecting  crystalline  forms  ? 

*  Beudant  Traite  Element,  de  Physique,  p.  86. 

t  Brande's  Manual  of  Chemistry,  3d  ed.,  vol.  i.  p.  16. 


GONIOMETER. 


295 


the  other  larger,  it  must  be  manifest  that  the  one  may  consist  of 
almost  any  number  of  degrees  less  than  90,  and  the  other  of  any 
number  below  180,  which  sum,  however,  must  be  the  amount  of 
the  two  angles  taken  together.  For  the  four  angles  of  the  crystal 
collectively,  will  be  equal  to  four  right  angles,  i.  e.,  90  X  4  =  360, 
or  the  number  of  degrees  of  a  circle  by  which  angles  are  measured. 

50.  Thus  the  primitive  form  of  carbonate  of  lime,  calcareous  spar, 
is  a  rhomboid  whose  faces  are  inclined  at  angles  of  105°  5',  and  74° 
5',  both  together  making  180°.     Tourmaline  has  for  its  primitive 
crystal  an  obtuse  rhomboid,  the  angle  of  which  is  113°  10',  and  in 
like  manner  other  minerals  have  their  peculiar  and  constant  forms, 
the  precise  nature  of  which  can  alone,  in  many  cases,  be  ascertained 
by  measuring  the  angles  of  the  crystal.* 

51.  Instruments  for  this  purpose,  called  goniometers,  are  chiefly 
of  two  kinds,  the  common  and  the  reflective  goniometer.  The  first 
and  simplest  of  these  instruments  consists  of  a  protractor,  or  semi- 
circular scale,  graduated  from  0  to  180,  with  a  small  pair  of  com- 
passes applied  to  it,  destined  to  receive  the  crystal  whose  angles 
are  to  be  measured. 

52.  One  arm  of  the  com- 
passes, F  G,  in  the  annexed 
figure,  forms  the  diameter  of 
the  semicircular  arc,  and  the 
other  arm,  A  B,  the  radius 
of  that  arc,  and  this  last  being 
moveable  on  the  pivot  /»,  the 
two  arms  may  be  made  to 
form  any  given  angle  with 
each  other.  The  transverse 
arm  is  grooved  or  slit  from  n 
to  r,  except  at  &,  where  there 
is  a  little-,  cross  piece  to 
strengthen  it.  By  means  of 
this  slit,  and  the  two  pins  ra 
and  n,  this  arm  may  be  slid  across  the  diameter  of  the  arc,  passing 

How  may  crystals  having  a  general  resemblance  be  found  to  differ  ? 

What  is  the  primitive  form  of  carbonate  of  lime? — of  the  tourmaline? 

By  what  instruments  are  the  angles  of  crystals  measured  ? 

What  is  the  ordinary  form  of  the  goniometer  ? 

Who  first  discovered  the  constancy  of  angles  in  crystals?  (See  note.) 

Describe  the  common  goniometer? 

*  Rome  de  PIsle  first  called  the  attention  of  mineralogists  to  the  remark- 
able fact,  "  that  notwithstanding  the  irregular  and  changeable  enlarge- 
ments of  certain  faces,  and  the  indistinct  formation  of  the  edges  between 
these  faces,  the  angle  at  which  they  meet  always  remains  constant,  This 
peculiarity  affords  one  of  the  most  distinctive  characters  which  minerals 
possess ;  one  by  which  the  mineralogist  is  frequently  led  immediately  to 
the  determination  of  a  species,  and  which,  therefore,  it  is  evidently  of  ex- 
treme importance  he  should  ascertain  with  precision." — Manual  of  Mine- 
ralogy, comprehending  the  more  Recent  Discoveries  in  the  Mineral  Kingdom. 
By  Robert  Allan,  F.R.S.E.,  M.G.S.  1834.  p.  16. 


296  CRYSTALLOGRAPHY. 

through  the  points  zero  and  180°.  The  pin  m  passes  through  a 
brass  knob  behind  the  arm  F  G,  which  is  attached  to  the  semi- 
circle at  N,  and  by  the  bar  O.  The  arm  A  B  has  a  groove  from 
C  to  B,  by  means  of  which,  when  necessary,  that  arm  may  be 
shortened,  by  sliding  it  upwards. 

53.  In  order  to  use  this  instrument,  it  is  merely  requisite  to 
place  the  crystal  to  .be  measured  between  the  compasses,.the  arms 
of  which  being  brought  in  exact  contact  with  the  planes  forming 
the  angle  required,  and  the  arm  A  B  applied  to  the  protractor,  the 
value  of  the  angle  may  be  read  off  at  the  fiducial  edge  z  s. 

54.  Though  this  instrument  is  serviceable  to  ascertain  to  a  given 
extent  the  angles  of  crystals,  it  is  far  inferior  in  accuracy  to  the 
reflective  goniometer,  invented  by  Dr.  Wollaston,  the  use  of  which, 
however,  requires  more  skill  and   attention  in  the   experimenter. 
For  an  account  of  the  latter,  and  of  the  method  of  employing  it, 
we  must  refer  the  reader  to  the  works  of  those  who  have  treated 
the  subject  of  crystallometry  more  fully  than  is  consistent  with 
the  limits  to  which  we  are  confined.* 

55.  Among  the  latest  and  most  important  improvements  in  crys- 
tallographical  mineralogy,  is  the  introduction  of  crystallometrical 
systems  :  as  the  tesseral ;  the  tetragonal,  or  square  pyramid  of 
Mohs  ;  the  rhombic,  or  oblong  pyramidal,  or  prismatic  of  Mohs  ; 
the   rhomboedral    of  Mohs,   or   hexagonal    of    Naumann ;     and 
the  monoklinoedral,  diklinoedral,  and    triklinoedral    of  the  last 
mentioned  writer.     Some  notion  may  perhaps  be  formed  of  the 
nature  of  these  distinctions  from  the  following  representation  : 

5G.  "  If  we  conceive  a  square  steeple  with  all  the  four  sides  of 
the  walls  and  roof  exactly  alike,  so  that  every  slope  and  face  which 
occurs  on  one  side  occurs  similarly  on  the  other  three,  we  have 
before  us  a  form  belonging  to  the  square  pyramidal  system.  If,  in- 
stead of  this,  we  imagine  a  house  of  which  the  two  ends  are  like 
each  other,  and  the  two  sides  also  precisely  like  each  other,  but 
different  from  the  former,  this  will  belong  to  the  oblong  prismatic 
or  rhombic  system.  If  again  we  conceive  a  triangular  pillar,  as  an 
ancient  tripod,  its  three  sides  being  similarly  cut  and  ornamented, 
this  will  belong  to  the  rhomboedral  system. f  In  fact,  its  three 
faces  may  be  terminated  by  slopes,  which  may  meet  and  form  an 
apex,  resembling  in  all  respects  the  apex  of  a  rhomboedron.  And 
if  each  of  its  three  faces  be  formed  into  an  edge,  by  planes  sloping 
to  the  right  and  left,  the  form  may  be  thus  converted  into  a  six- 
sided  pillar  with  no  loss  of  its  regularity. 

On  what  principle  does  the  goniometer  of  Wollaston  operate  ? 
What  constitutes  the  latest  improvement  in  crystallography  ? 
Illustrate  the  views  of  Naumann  on  this  subject? 

*  A  description  of  Dr.  Wollaston's  goniometer,  with  the  mode  of  using 
it,  illustrated  by  a  diagram,  will  be  found  in  Brande's  Manuel  of  Chemis- 
try, vol.  i.  pp  10 — 13  ;  or  in  Mrs.  Lowry's  Conversations  on  Mineralogy, 
2d  ed.,  vol.  i.  pp.  71—75. 

t  The  rhomboedral  and  rhomoic  systems  are  quite  distinct.  A  rhombic 
prism  has  its  base  &  rbomb ;  a  rhomboedron  has  all  its  sides  equal  rhombs. 


TESSULAR  SYSTEM.  297 

57.  "  If  we  conceive  the  form  of  the  house  of  which  we  spoke, 
as  representing  the  prismatic  system,  to  be  made  less  regular,  by 
sloping  its  end  walls  in  the  direction  of  one  end,  we  have  the 
monoklinoedral  system,  and  if  the  side  walls  slope  also,  we  may 
have  thus  the  diklinoedral  and  triklinoedral  forms. 

"The  tesseral  or  tessular  system  includes  the  forms  which 
are  derived  from  the  regular  solids  of  geometry,  the  cube,  the 
octaedron,  the  dodecaedron. 

58.  "  This  distinction  of  different  kinds  of  forms  is  one  founded 
on  the  most  general  relation  of  their  parts,  and  regulated  by  the 
degree  and  kind  of  their  symmetry.     The  claim  of  priority  in  in- 
troducing this  classification  of  forms  has  been  a  subject  of  contro- 
versy between    Prof.   Mohs   and    Prof.   Weiss.      However  this 
question  may  be  decided,  the  merit  of  this  valuable  simplification 
rests  between  them  ;  and  all  must  allow  the  propriety  with  which 
Prof.  Naumann,  of  Freiberg,  the  author  of  the  best  recent  system 
of  crystallography,  has  dedicated  his  work  "  to  Mohs  and  Weiss,  the 
Coryphsei  of  German  Crystallographers.*" 


Explain  the  terms  monoklinoedral  and  diklinoedral? 
To  what  two  philosophe 
cryatallometrical  systems  ? 


To  what  two  philosophers  are  we  indebted  for  the  introduction  of  the 
Isv 


*  Report  of  Brit  Assoc.  1832,  pp.  328,  329.  For  a  further  explanation 
of  the  crystallographic  system  of  Prof.  Mohs,  see  Allan's  Manual  of  Mine- 
ralogy, Introd.,  pp.  18,  19. 


Works  relating  to  the  department  of  Crystallography. 

Turner's  Chemistry.     Phila.  edition,     pp.  424 — 433. 

Webster's  Manual  of  Chemistry  on  the  basis  of  Brande's.  1  vol. 
8vo.  p.  9. 

Gorham's  Chemistry.  1  vol.  8vo.  pp.  8 — 21;  with  a  plate 
illustrating  the  hypotheses  of  Wollaston  and  Daniell. 

Rome  Delisle  Crystallographies.     3  vols.  12  mo.     1783. 

Huay  Crystallographie.  2  vols.  8vo. ;  and  an  astlaof  84  plates, 
illustrating  his  views  both  synthetically  and  analytically. 

Bournon  Traite  de  Mineralogie.     3  vols.  8vo. 


GEOLOGY. 

1.  GEOLOGY  is  a  science  exclusively  of  modern  origin,  pre- 
senting to  our  notice  a  series  of  facts  and  deductions  resulting 
from  researches  almost  entirely  of  a  recent  date.     It  relates  to 
bodies,  multitudes  of  which  must  necessarily  have  attracted  the 
attention  of  mankind  in  all  ages  and  countries,  and  many  of  whose 
properties  have  been  frequently  and  closely  investigated  ;  but  it 
is  the  peculiar  purpose  of  this  branch  of  philosophy  to  develope 
the  relations  of  natural  substances  as  contributing  to  form  the  ter- 
restrial globe ;  and  hence  the  interest  or  importance  of  any  given 
object,  as  a  block  of  granite  or  marble,  a  nodule  of  flint,  a  petri- 
fied shell,  a  fragment  of  fossil  bone,  or  any  other  natural  produc- 
tion, is  not  decided   on  by  the  geologist  with  reference  to  its 
chemical  composition  or  peculiar  structure,  simply  considered  ; 
but  chiefly  according  to  the  indications  it  may  afford  concerning 
the  mode  of  its  derivation,  and  the  situation  it  originally  occupied, 
as  composing  a  part  of  the  crust  or  exterior  of  the  earth. 

2.  The  proper  object  and  design  of  geology,  therefore,  must  be 
the  study  of  the  general  structure  of  what  may  be  termed  the  shell 
of  the  terrestrial  globe ;  for  though  speculations  relative  to  the 
nature  of  the  internal  strata,  or  even  the  nucleus  of  the  mass,  are 
not  wholly  inadmissible,  yet  they  must  ever  be  regarded  as  of 
secondary  importance,  and  should  be  no  further  pursued  than  they 
are  warranted  by  those  facts  and  appearances  which  come  imme- 
diately under  our  observation.     This  consideration,  however,  was 
entirely  lost  sight  of  by  those  earlier  writers,  who  either  incident- 
ally or  professedly  treated  of  the  structure  of  the  earth.    It  would 
be  profitless  labour  to  pursue  at  length  the  reveries  of  a  host  of 
bold  theorists,  who  sprung  up  between  the  period  of  the  revival  of 
learning  in  Europe  and  the  middle  of  the  last  century  ;  and  whose 
systems  of  cosmogony,  as  they  vainly  styled  them,  have  by  more 
sober  inquirers  been  justly  stigmatized  as  romances,  indebted  for 
their  existence  to  the  prolific  powers  of  imagination. 

3.  But  while  so  many  philosophers  were  busily  employed  in 
endeavouring  to  erect  systems  of  cosmogony  on  the  basis  of  their 
own  most  imperfect  knowledge  of  the  nature  of  mineral  bodies, 
or  drew  their  ephemeral  theories  solely  from  imagination,  there 
were  some  who  more  wisely  applied  themselves  to  the  observa- 

To  what  era  in  philosophy  does  the  science  of  geology  pertain  ? 

What  is  the  peculiar  province  of  this  science? 

How  does  the  geologist  differ  from  the  chemist  or  mineralogist  in  his  es« 
timate  of  a  natural  object? 

What  part  of  the  globe  constitutes  the  proper  object  of  geological  inves* 
tigation  ? 

How  are  theoretical  speculations  to  be  regarded  in  geology  ? 

What  name  was  griven  to  geological  theories  before  the  period  of  exact 
observation  ? 

898 


THEORIES  OF  LEIBNITZ  AND  LEHMAN.  299 

tion  of  nature,  and  to  the  collection  of  correct  iifformation  relative 
to  the  productions  of  the  mineral  kingdom  in  general,  and  espe- 
cially concerning  those  fossils  which  exhibit  traces  of  having 
originated  from  organization. 

4.  Bernard  Palissy,  a  potter  of  Saintes,  towards  the  end  of  the 
sixteenth  century,  is  said  by  Fontenelle  to  have  been  the  first  who 
ventured  to  assert  in  Paris,  in  opposition  to  the  prevailing  opinion, 
that  petrified  shells  were  the  remains  of  testaceous  animals  that 
had  formerly  lived  in  the  sea,  and  that  all  these  were  not  depo- 
sited at  the  universal  deluge.    He  wrote  on  the  Origin  of  Springs 
from  Rain-water,  and  other  scientific  works  ;  and  he  had  the  merit 
of  displaying  much  juster  views  of  the  operations  of  nature  than 
most  of  his  contemporaries,  though  his  ideas  met,  in  his   own 
time,  with   a  very  faint  reception.      Similar   notions  were   ad- 
vocated by  Nicholas  Steno,  a  Dane,  who  became  professor  of 
anatomy  at  Padua  in  Italy,  in  1669  ;  and  Hooke  and  Ray,  in  Eng- 
land, distinguished  themselves  by  opposing  facts  to  visionary 
theories. 

5.  Leibnitz,  in  his  Protogaea,  published  in  1680,  advanced  the 
bold  hypothesis,  that  the  earth  was  originally  a  burning  luminous 
mass,  the  gradual  refrigeration  of  which  produced  the  primitive 
rocks,  forming  at  first  a  solid  crust,  and  this  being  ruptured,  owing 
to  irregular  contraction,  the  fragments  fell  into  the  universal  ocean 
formed  by  the  condensation  of  vapours  on  the  surface  of  the  globe. 
He  proceeds  to  trace  the  production  of  inundations,  convulsions,  and 
attrition  of  solid  matter,  by  its  subsequent  deposition  constituting 
the  various  kinds  of  sedimentary  or  stratified  rocks.     Hence,  he 
observes,  may  be  conceived  a  double  origin  of  primitive  masses : 
(1.)  By  cooling  after  igneous -fusion ;  (2.)  By  re-concretion  from 
aqueous  solution.*     "  Here,"  says    Mr.  Conybeare,  "  we  have 
distinctly  stated  the  great  basis  of  every  scientific  classification 
of  rock  formations."!  The  grand  feature  of  the  theory  propounded 
by  Leibnitz,  relative  to  the  candescent  state  and  gradual  cooling 
of  the  earth,  was  adopted  not  only  by  Whiston,  but  likewise 
more  recently  by  Buffon,  Deluc,  and  other  theorists. 

6.  Among  those  men  of  science  who  contributed  to  the  im- 
provement of  geology,  by  their  researches  into  the  actual  struc- 
ture of  the  earth's  crust,  was  Tilias,  a  Swede ;  who,  aware  of  the 
importance  of  an  exact  knowledge  of  mineral  bodies,  published 

Who  is  said  to  have  first  made  collections  of  fossil  remains  ? 
What  Danish  and  English  writers  followed  a  similar  coarse  ? 
What  view  of  the  cause  of  rock  formations  was  taken  by  Leibnitz? 
How  does  that  view  correspond  with  the  present  received  opinions? 
What  Swedish  writer  early  contributed  to  the  stock  of  facts  relating  to 
geology  ? 

*  "  Unde  jam  duplex  origo  intelligitur  primonim  corporum,  una,  cum  ab 
ignis  fusione  refrigescerent,  altera,  cum  reconcrescerent  ex  solutione  aqua- 
rum." 

t  Progress,  Actual  State,  and  Ulterior  Prospects  of  Geological  Science, 
in  Report  of  British  Association  for  1832,  p.  368. 


300  GEOLOGY. 

Hn  1750  several  typographical  descriptions  illustrative  of  the  geo 
logy  of  certain  districts  in  Sweden.  He  was  followed  by  Leh- 
man, a  German  mineralogist,  director  of  mines  in  Prussia,  who, 
in  an  Essay  towards  a  Natural  History  of  the  Strata  of  the  Earth, 
1750,  proposed  a  division  of  mountains  into  those  formed  before  the 
creation  of  animals,  and  containing  no  fragments  of  other  rocks ; 
mountains  which  were  derived  from  the  partial  destruction  of  the 
primary  rocks  by  a  general  revolution  ;  and  those  which  resulted 
from  local  revolutions,  and  in  part  from  the  Noachian  deluge. 

7.  Many  other  writers    now  appeared,   who    advantageously 
directed  their  attention  to  the  investigation  of  particular  topics 
connected  with  this  subject;  as  the  causes  and  phenomena  of 
earthquakes  and  volcanos,  the  formation  of  deltas  or  low  tracts 
at  the  mouths  of  rivers,  the  actual  structure  and  position  of  the 
mineral  strata,  and  the  description  of  fossil  remains  of  animal  or 
vegetable  origin.     Among  those  who  rendered  important  services 
to  the  cause  of  science  by  advancing  general  views  of  the  theory 
of  the  earth,  were  Dr.  James  Hutton,  of  Edinburgh,  and  Profes- 
sor Werner,  of  Freyberg,  in  Saxony.     These  celebrated  philoso- 
phers produced  systems,  in  one  respect,  diametrically  opposite  to 
each  other  ;  for  while  Hutton  attributed  the  formation  of  the  older 
rocks  entirely  to  the  agency  of  fire,  Werner  insisted  that  they 
originated  from  solution  in  a  liquid. 

8.  The  German  geologist  deserves  the  credit  of  having  directed 
the  attention  of  his  pupils  to  the  constant  relations  of  mineral 
groups,  and  their  regular  order  of  superposition  ;  distinguishing 
the  classes  of  primary  rocks,  or  those  destitute  of  organic  remains, 
as  granite  and  gneiss ;  transition  or  secondary  rocks,  formed  from 
the  disintegration  of  the  preceding,  and  occasionally  exhibiting 
traces  of  organic  remains,  as  grey  wacke,  a  mechanical  compound 
of  agglutinated  fragments ;  floetz  or  tertiary  rocks,  including  the 
coal  strata,  chalk,  and  freestone,  some  of  which  abound  in  organic 
relics ;  and  besides  these,  alluvial  strata  and  volcanic  rocks,  the 
latter  of  which  he  seems  to  have  regarded  as  of  little  importance, 
for  he  asserted  that  in  the  primeval  ages  of  the  world  there  were 
no  volcanos. 

9.  The  great  merit  of  Hutton  consists  in  his  having  demon- 
strated the  igneous  origin  of  basalt,  and  other  trap  rocks ;  the 
high  probability  that  granite  is  derived  from  the  same  source  ;  and 
that  the  other  primary  non-fossilliferous  rocks  have  been  more  or 
less  subjected   to  the  agency  of  fire.     "  The  ruins  of  an  older 
world,"  said  Hutton,  "  are  visible  in  the  present  structure  of  our 
planet,  and  the  strata  which  now  compose  our  continents  have 
been  once  beneath  the  sea,  and  were  formed  out  of  the  waste  of 

What  was  the  division  of  mountains  proposed  by  Lehman? 
What  two  writers  attempted  to  reduce  to  geological  systems  the  obser- 
vations of  naturalists  before  the  end  of  the  eighteenth  century? 
What  is  the  difference  of  their  views  ? 

Who  formed  the  division  of  rocks  into  primary,  secondary,  and  tertiary  ? 
To  what  peculiar  merit  is  the  English  theorist  entitled  ? 


THEORIES  OF  THE  EARTH.  301 

pre-existing  continents.  The  same  forces  are  still  destroying,  by 
chemical  decomposition  or  mechanical  violence,  even  the  hardest 
rocks,  and  transporting  the  materials  to  the  sea,  where  they  are 
spread  out,  and  form  strata  analogous  to  those  of  more  ancient 
date.  Although  loosely  deposited  along  the  bottom  of  the  ocean, 
they  become  afterwards  altered  and  consolidated  by  volcanic  heat, 
and  then  heaved  up,  fractured  and  contorted."* 

10.  The  theory  of  Hutton  was  admirably  illustrated  and  ably 
supported   by   Professor  Playfair,  of  Edinburgh,  while  it  was 
assailed  by  Murray,  Kirwan,  Deluc,  and  others,  a  violent  contro- 
versy being  maintained  between  the  partizans  of  Werner,  who 
were  called  Neptunists,  as  ascribing  the  formation  of  all  rocks  to 
water;  and  those  of  Hutton,  styled  Vulcanists,  because  they 
attributed  the  original  formation  of  rocks  to  fire.   The  Neptunists, 
for  a  time,  constituted  by  much  the  more  numerous  party  ;  but  in 
the  course  of  these  discussions,  it  was  at  length  perceived  that 
speculation  had,  on  both  sides,  been  carried  further  than  was  war- 
ranted by  the  extent  of  existing  information ;    and  that  while 
neither  the  theory  of  Werner,  nor  that  of  Hutton,  could  be  consi- 
dered as  affording  an  explanation  of  all  the  phenomena,  or  making 
near  approaches  to  perfection,  there  were  many  points  with  re- 
spect to  which  the  researches  and  observations  of  both  these  phi- 
losophers contributed  to  the  extension  of  our  knowledge,  and  the 
improvement  of  the  science. 

11.  "A  new  school  at  last  arose,  who  professed  the  strictest 
neutrality  and  the  utmost  indifference  to  the  systems  of  Wer- 
ner and   Hutton,  and  who  resolved  diligently  to  devote  their  la- 
bours to  observation.   The  reaction,  provoked  by  the  intemperance 
of  the  contending  parties,  now  produced  a  tendency  to  extreme 
caution.     Speculative  views  were  discountenanced  ;  and  through 
fear  of  exposing  themselves  to  the  suspicion  of  a  bias  towards  the 
dogmas  of  a  party,  some  geologists  became  anxious  to  entertain 
no  opinion  whatever  on  the  causes  of  phenomena,  and  were  in- 
clined to  scepticism,  even  where  the  conclusions  deducible  from 
observed  facts  scarcely  admitted  of  reasonable  doubt. 

12.  "  But  although  the  reluctance  to  theorize  was  carried  some- 
what to  excess,  no  measure  could  be  more  salutary  at  such  a  mo- 
ment than  a  suspension  of  all  attempts  to  form  what  were  termed 
theories  of  the  earth.     A  great  body  of  new  data  was  required,  and 
the  Geological  Society  of  London,  founded  in  1807,  conduced 
greatly  to  the  attainment  of  this  desirable  end.     To  multiply  and 
record  observations,  and  patiently  to  await  the  result  at  some  fu- 

What  did  Hutton  suppose  to  have  been  the  origin  of  the  present  conti- 
nents ? 

Who  have  illustrated  the  theory  of  Hutton? 

What  course  was  adopted  to  free  the  science  of  geology  from  disputes 
about  theories  ? 

What  was  the  effect  of  that  course  ? 

*  Ly«ll's  Principles  of  Geology,  3d  ed.,  1834,  vol.  i.  pp.  88,  89;  from 
Hutton 's  Theory  of  the  Earth- 

20 


302  GEOLOGY. 

ture  period,  was  the  object  proposed  by  them ;  and  it  was  their 
favourite  maxim,  that  the  time  was  not  yet  come  for  a  general 
system  of  geology,  but  that  all  must  be  content  for  many  years 
to  be  exclusively  engaged  in  furnishing  materials  for  future  gene- 
ralizations. By  acting  up  to  these  principles  with  consistency, 
they  in  a  few  years  disarmed  all  prejudice,  and  rescued  the 
science  from  the  imputation  of  being  a  dangerous,  or  at  best  but 
a  visionary  pursuit."* 

13.  One  train  of  research  which  was  now  pursued  with  great 
ardour,  and  which  contributed  much  to  the  improvement  of  science, 
was  respecting  the  nature  of  the  organic  remains,  which  were 
found  imbedded  in  various  strata  in  different  parts  of  the  world. 
Cuvier,  the  celebrated  anatomist  and  zoologist,  professor  of  natu- 
ral history  at  Paris,  acquired  great  distinction  by  the  number, 
accuracy,  and  importance  of  the  discoveries  which  he  made  rela- 
tive to  the  generic  and  specific  characters  of  the  animals,  frag- 
ments of  whose  bones,  and  other  constituent  parts,  occurred  to 
notice  in  the  course  of  his  long  and  laborious  investigations.    He 
ascertained  that  numerous  living  beings  of  different  classes,  which 
hav,p  no  existing  analogues,  once  inhabited  the  surface  of  the 
globe ;  and  that  the  relative  priority  of  the  several  strata  might, 
to  a  certain  extent,  be  inferred  from  the  characters  of  the  organic 
remains  included  in  them. 

14.  Among  the  recent  cultivators  of  this  branch  of  science 
besides   Cuvier,  may  be  named  Alex.  Brongniart,  Lamouroux, 
Lamarck,  Deshayes,  Marcel  de  Serres,  Brocchi,  Goldfuss,  Parkin- 
son, Buckland,  Conybeare,  J.  S.  Miller,  Mantell,  Lonsdale,  Say, 
Morton,  and  Harlan,  who  devoted  their  attention  chiefly  to  fossil- 
ized animal  remains ;  and  Adolphe  Brogniart,  Witham,  Lindley, 
and  W.  Hutton,  whose  investigations  have  been  especially  directed 
to  botanical  oryctology.     The  results  of  their  researches  relative 
to  these  subjects,  and  those  of  other  geologists  concerning  the 
mineralogical  structure  and  position  of  rocks  and  mountains,  and 
the  modifying  influence  of  existing  causes  on  the  surface  of  the 
earth,  have  greatly  contributed  to  the  augmentation  of  our  know- 
ledge of  the  nature  and  arrangement  of  the  superficial  strata  of 
the  planet  on  which  we  dwell,  which  must  be  regarded  as  the 
only  sure  foundation  of  a  true  system  of  geognosy,  which  may 
verify  or  overturn  the  conjectural  speculations  of  those  philoso- 
phers who  wrote  during  the  infancy  of  the  science. 

15.  "  When  we  compare  the  result  of  observations  in  the  last 
thirty  years,  with  those  of  the  three  preceding  centuries,  we  can- 
To  what  particular  branch  of  the  subject  were  inquiries  directed  ? 
Who  took  the  lead  in  those  researches  ? 

What  has  been  the  effect  of  the  inductive  observations  of  modern  phi- 
losophers ? 

What  estimate  is  to  be  put  upon  the  results  of  these  inquiries  compared 
with  those  of  former  years? 

*  tyell'g  Principles  of  Geology,  vol.  i.  pp,  102,  103, 


I 

PROGRESS  OF  GEOLOGICAL  SCIENCE.  303 

not  but  look  forward  with  the  most  sanguine  expectations  to  the 
degree  of  excellence  to  which  geology  may  be  carried,  even  by 
the  labours  of  the  present  generation.  Never,  perhaps,  did  any 
science,  with  the  exception  of  astronomy,  unfold,  in  an  equally 
brief  period,  so  many  novel  and  unexpected  truths,  and  overturn 
so  many  preconceived  opinions.  The  senses  had  for  ages  declared 
the  earth  to  be  at  rest,  until  the  astronomer  taught  that  it  was 
carried  through  space  with  inconceivable  rapidity.  In  like  man- 
ner was  the  surface  of  this  planet  regarded  as  having  remained 
unaltered  since  its  creation,  until  the  geologist  proved  that  it  had 
been  the  theatre  of  reiterated  change,  and  was  still  the  subject  of 
slow  but  never-ending  fluctuations. 

16.  The  discovery  of  other  systems  in  the  boundless  regions  of 
space  was  the  triumph  of  astronomy ; — to  trace  the  same  system 
through  various  transformations — to  behold  it  at  successive  eras 
adorned  with  different  hills  and  valleys,  lakes  and  seas,  and  peo- 
pled with  new  inhabitants,  was  the' delightful  meed  of  geological 
research.  By  the  geometer  were  measured  the  regions  of  space, 
and  the  relative  distances  of  the  heavenly  bodies; — by  the  geolo- 
gist myriads  of  ages  were  reckoned,  not  by  arithmetical  computa- 
tion, but  by  a  train  of  physical  events — a  succession  of  pheno- 
mena in  the  animate  and  inanimate  worlds — signs  which  convey  to 
our  minds  more  definite  ideas,  than  figures  can  do,  of  the  immen- 
sity of  time."* 

17.  "  By  the  discoveries  of  a  new  science,  (the  very  name  of 
which  has  been  but  a  few  years  ingrafted  on  our  language,)  we 
learn  that  the  manifestations  of  God's  power  on  earth,  have  not  been 
limited  to  the  few  thousand  years  of  man's  existence.     The  geo- 
logist tells  us,  by  the  clearest  interpretation  of  the  phenomena 
which  his  labours  have  brought  to  light,  that  our  globe  has  been 
subject  to  vast  physical  revolutions.  He  counts  his  time,  not  by 
celestial  cycles,  but  by  an  index  which  he  has  found  in  the  solid 
framework  of  the  globe  itself.     He  sees  a  long  succession  of 
monuments,  each  of  which  may  have  required  a  thousand  ages 
for  its  elaboration.  He  arranges  them  in  chronological  order,  ob- 
serves on  them  the  marks  of  skill  and  wisdom,  and  finds  within 
them  the  tombs  of  the  ancient  inhabitants  of  the  earth. 

18.  He  finds  strange  and  unlooked-for  changes  in  the  forms 
and  fashions  of  organic  life  during  each  of  the  long  periods  he 
thus  contemplates.    He  traces  these  changes  backwards  through 
each  successive  era,  till  he  reaches  a  time  when  the  monuments 
lose^all  symmetry,  and  the  types  of  organic  life  are  no  longer  seen. 
He  has  then  entered  on  the  dark  age  of  nature's  history ;  and  he 
closes  the  old  chapter  of  her  records.     This  account  has  so  much 

What  two  great  errors  have  astronomy  and  geology  removed  ? 
What  discoveries  have  they  respectively  effected  ? 

What  is  the  relative  nature  of  organized  beings  at  present  compared  to 
that  of  forirar  geological  periods  ? 

*  Lyell's  Principles  of  Geology,  vol.  i.  pp.  106,  107. 


304  GEOLOGY. 

of  what  is  exactly  true,  that  it  hardly  deserves  the  name  of  figura- 
tive description."* 

Figure  and  Magnitude  of  the  Earth,  its  Mean  Density,  Superficial 
Conformation  and  Structure. 

19.  Before  we  proceed  to  describe  the  present  state  of  the 
crust  of  the  earth,  and  investigate  the  probable  causes  of  its  ori- 
gin and  structure,  with  the  nature  of  the  strata  or  more  irregular 
masses  of  which  it  is  composed,  it  will  be  requisite  to  notice 
those  facts  concerning  the  general  figure,  dimensions,  and  den- 
sity of  the  terrestrial  globe,  and  of  the  contour  of  its  surface,  as  a 
body  of  land  and  water,  for  a  knowledge  of  which  we  are  in- 
debted to  the  researches  of  astronomers  and  geographers. 

20.  That  the  figure  of  the  earth  is  spherical,  or  rather  spheroidal, 
though  a  matter  of  dispute  among  ancient  philosophers,  and  still 
disbelieved  by  the  vulgar,  is  now  admitted  as  an  incontestable 
truth  by  all  well  informed  persons.     The  curved  surface  of  the 
sea  when  viewed  from  the  shore,  and  the  observation  that  the 
upper  rigging  of  an  approaching  ship  becomes  visible  to  a  distant 
spectator  before  the  hull  comes  in  sight,  while  the  hull  first  dis- 
appears when  the  vessel   is  receding,  prove  that  the  object  in 
question  must  be  moving  in  the  circumference  of  a  great  circle. 

21.  A  similar  conclusion   may  be   drawn  from  the  changing 
aspect  of  the  heavens  to  an  observer  travelling  from  north  to  south. 
For  though  the  stars  and  the  constellations  they  form  will  be 
found  to  maintain  the  same  relative  positions  with  respect  to 
those  around  them,  and  the  points  on  which  the  celestial  dome 
appears  to  revolve  remain  unaltered,  yet  the  angle  which  its  axis 
of  revolution  forms  with  the  horizon  continually  lessens ;  and  thus 
any  star,  which  at  the  place  whence  it  started,  seemed  to  the  ob- 
server to  have  reached  its  greatest  elevation  to  the  south  of  the  point 
directly  above  his  head,  now  that  he  has  altered  his  position, 
will  appear,  when  highest,  on  the  north  of  that  point ;  clearly  in- 
dicating that  his  path  on  the  earth's  surface  has  not  been  a  right 
line,  but  a  curve,  of  which  the  convexity  is  turned  towards  the 
sky,  corresponding,  in  fact,  more  or  less,  with  a  meridian  of  lon- 
gitude.    The-  appearance  of  the  moon  when  eclipsed,  likewise 
furnishes  demonstrative   proof  of  the  spheroidal  figure   of  the 
earth,  for  lunar  eclipses  are  caused  by  its  circular  shadow  inter- 
cepting the  light  of  the  sun  from  the  moon's  disk. 

What  geographical  subjects  are  connected  with  geological  science? 
What  evidence  have  we  of  the  spherical  form  of  the  earth? 
What  astronomical  observations  demonstrate  this  fact  ? 
What  particular  celestial  phenomenon  occur  in  going  from  a  north  to  a 
south  latitude  ? 

*  Discourse  on  the  Studies  of  the  University,  by  Adam  Sedewick,  M.A 
F.R.S.,  Woodwardian  Professor,  and  Fellow'  of  Trin.  Coll.  «mb.,  1834, 
pp.  25,  26. 


FIGURE  OF  THE  EARTH.  305 

22,  It  has  been  found,  however,  both  from  astronomical  and 
geodesical  observations,  that  the  earth  is  not  a  perfect  sphere, 
but  that  its  figure  is  that  of  an  oblate  spheroid,  or  such  a  solid 
as  would  be  formed  by  the  revolution  of  a  fluid  mass  in  open 
space.     Huygens  and  Newton  deduced  the  real  figure  of  the  earth 
from  the  doctrine  of  central  forces  of  bodies  revolving  in  circles, 
and  their  conclusions  were  subsequently  verified  by  actual  mea- 
surements of  degrees  of  the  meridian   in  various  latitudes.     It 
appears,  however,  that  though  the  polar  diameter  of  the  earth  is 
certainly  smaller  than  its  equatorial  diameter,  the  exact  difference 
between  them  has  not  yet  been  accurately  ascertained.     It  has 
been  estimated  by  some  at  ,^-j  part  of  the  equatorial  axis,  by 
others  at  -^{-^  part;  but  Professor  Wallace  says:    "  We  may  as- 
sume, without  sensible  error,  that  the  equatorial  axis  is  to   the 
polar  as  334  to  333  ;  the  difference,  therefore,  of  the  serniaxes, 
compared  with  the  equatorial  radius,  will  be  1  part  in  334.     The 
fraction  of  ^T,  that  is,  the  difference  of  the  semiaxes  divided  by 
the  equatorial  radius,  is  called  the  compression  of  the  earth  at  the 
poles."* 

23.  The  determination  of  the  figure  of  the  earth  leads  to  con- 
clusions respecting  its  mean  density,  which  also  has  within  cer- 
tain limits  been  sufficiently  ascertained.     Sir  Isaac  Newton,  rea- 
soning on  the  supposition  of  uniform  density  in  the  earth,  esti- 
mated its  compression  at  the  poles  as  -^\^  of  its  diameter.     Now, 
since  experiment  has  demonstrated  that  the  compression  is  less, 

In  what  manner  do  eclipses  of  the  moon  demonstrate  the  spherical  form 
of  the  earth  ?  What  is  the  true  figure  of  the  earth? 

What  is  the  relation  between  the  equatorial  and  polar  diameters  of  the 
earth  ? 

What  has  been  assigned  by  Newton  as  the  compression  of  the  earth  at 
the  poles  on  the  supposition  of  a  uniform  density  ? 

*  Murray's  Encyclopaedia  of  Geography,  1834,  part  ii.  b.  i.  ch.  19,  p.  128. 

"  As  the  earth  has  a  movement  of  rotation  about  its  axis,  all  its  parts 
will  be  animated  with  a  certain  degree  of  centrifugal  force,  which  must 
be  more  or  less  considerable  as  the  parts  approach  or  are  distant  from  'ha 
axis.  Under  the  equator  will  be  the  points  of  greatest  distance  from  iho 
axis,  and  the  centrifugal  force  directly  opposed  to  that  of  weight  or  gravi- 
tation, ought  to  reduce  the  latter  there  more  than  at  any  oij^r  place  ;  and 
at  parts  intermediate  between  the  poles  and  the  equator,  the  diminution 
of  weight  ought  to  become  less  sensible,  in  proportion  as  they  are  nearer 
the  poles.  At  either  pole  the  centrifugal  force  will  vanish,  and  bodies 
will  have  the  same  weight  as  if  the  earth  were  at  rest. 

"  As  gravity  must  be  normal  at  the  surface  of  the  sea,  and  as  it  is  the 
resultant  of  terrestial  attraction  and  centrifugal  force,  it  will  be  obvious 
that  it  must  vary  at  different  places;  and  that  if  the  earth  wns  originally 
a  fluid.lt  could  not,  in  consequence  of  its  rotation,  preserve  the  form  of  a 
sphere,  but  that  it  must  assume  that  of  a  flattened  spheroid,  which  would 
be  generated  by  the  revolution  of  an  ellipsis  round  its  smaller  axis. 
This  also  is  demonstrated  by  experience,  and  that  the  flattening  at  the 
poles  renders  the  axis  l-310th  less  than  the  diameter  at  the  equator." — 
Francfp.nr  Tr&Mde  Micaniqme  EUmenlaire,  1825,  pp.  287,  288.  See  Scien- 
tific ClassBook.pt.  i.  Mechanics,  Nos.  10G,  107,  and  114  to  122. 

a  0-3 


306  GEOLOGY. 

amounting  at  most  to  ^  it  may  be  concluded  from  the  observa- 
tions of  Clairault,  that  if  the  earth  is  a  spheroid  of  equilibration,  it 
is  denser  in  the  interior  than  at  its  surface  ;  and  from  the  experi- 
ments of  Dr.  Maskelyne  and  Mr.  H.  Cavendish,*  it  has  been 
inferred  that  the  mean  density  of  the  earth  is  about  five  times  that 
of  water,  and  therefore  double  that  of  the  substances  which  com- 
pose the  crust  of  the  earth,  collectively  considered. 

24.  Since  then  the  mean  density  of  the  terrestrial  globe  is  so 
much  superior  to  that  of  its  superficial  strata,  it  follows  that  the 
interior  or  central  parts  must  be  composed  of  more  dense  mate- 
rials than  the  exterior.     On  a  subject  so  open  to  speculation  as 
the  constitution  of  the  nucleus  of  the  earth,  a  variety  of  conjec- 
tures, as  might  be  expected,  have  been  hazarded.     The  superior 
density  of  the  interior  parts  of  the  earth  compared  with  the  exte- 
rior, has  induced  some  to  conclude  that  the  nucleus  of  the  earth 
must  consist  of  some  substance  or  substances  naturally  possess- 
ing high  specific  gravity,  like  certain  of  the  metals.     "  It  can  be 
neither  gas  nor  water,"  says  Dr.  Bertrand,  "  which  constitutes 
the  interior  mass,  nor  yet  the  heaviest  stony  substances  with 
which  we  are  acquainted,  for  on  this  last  supposition,  the  entire 
spheroid  would  have  but  one-third  or  one-fourth  of  the  weight 
which  has  been  attributed  to  it  from  calculation  ;  therefore  it  must 
be  composed  of  matter  as  ponderous  as  the  heaviest  metals."f 

25.  This  ingenous  speculator,  however,  in  reprobating  the  hy- 
pothesis of  a  fluid  or  gaseous  nucleus  of  the  earth,  has  entirely 
neglected  the  consideration  of  the  relative  compressibility  of  elas- 
tic fluids  compared  with  bodies  which  on  the  surface  of  the  earth 
possess  superior  density.    Mr.  Colebroke,  in  a  paper  published  in 
Brande's  Journal  of  Science,  advanced  some  curious  and  interest- 
ing speculations  on  the  internal  portions  of  the  earth,  designed  to 
show  that  they  may  consist  of  air  and  water,  reduced  by  compres- 
sion to  extraordinary  degrees  of  density.     He  observes,  that  "  At 
a  certain  assignable  depth  water  may  have  a  density  greater  than 
that  of  those  solids  which  are  most  abundant  in  the  crust  or  shell 
of  the  terrestrial  globe.     Hence  it  would  follow  that  water  at  a 
very  great  depth  would  be  capable  of  floating  bodies  which  at  the 
surface  sink  by  their  superior  weight,  provided  density  and  spe- 
cific gravity  increase  much  less  rapidly  in  the  solid  than  in  the 
liquid,  unde^corresponding  degrees  of  compression. 

26.  Let  a  sphere  now  be  supposed,  having  the  same  mean  tem- 
perature of  its  mass,  and  exclusively  composed  of  gas ;  for  in- 

What  did  Maskelyne  and  Cavendish  demonstrate  in  regard  to  the  mean 
density  of  the  globe? 

To  what-supposition  lias  thie  result  led  ? 

What  were  Bertrand's  views  of  this  subject? 

What  are  the  calculations  of  Colebrooke  on  the  compressibility  of  air 
and  water  ? 

When  might  heavy  solids  be  found  to  float  in  water  ? 

*  See  Scientific  Class  Book,  pt  L  pp.  40,  41. 
t  Lett  «ur  Ifis  Rev-  du  Globe,  p.  40. 


STRUCTURE  OF  THE  EARTH.  307 

stance,  atmospheric  air.  It  can  be  conceived  that  this  gas,  more 
compressible  than  a  liquid,  may  in  obedience  to  the  power  of  gra- 
vity, acting  directly  and  likewise  mediately,  by  superincumbent 
pressure,  be  so  distributed  in  the  sphere,  as  that  the  density  and 
consequent  weight  of  the  compressed  gaseous  fluid  at  the  centre 
of  the  sphere,  and  to  a  certain  extent  around,  will  be  greater  than 
that  of  the  liquid  in  a  like  position  within  the  globe  before  men- 
tioned. It  would  be  capable  then  of  sustaining,  in  a  liquid  form, 
water  introduced  into  it.  Let  these  suppositions  be  combined, 
and  a  ball  be  next  imagined,  composed  of  a  gaseous  fluid,  and  of 
a  liquid  with  solids  interspersed. 

27.  It  is  easy  to  conceive  the  relative  compressibility  of  these 
substances,  and  the  actual  compression  of  them  to  be  such  that 
the  entire  portion  around  the  centre  may  be  occupied  by  highly 
condensed  gas,  encompassed  by  a  liquid  mass,  which  is  pervaded 
by  a  gaseous  fluid,  both  decreasing  in  density  upwards ;  and  beyond 
the  liquid  surface  surrounded  by  an  atmosphere  consisting  of  gas 
penetrated  by  aqueous  vapour.     Solid  substances  sparingly  scat- 
tered in  such  a  fluid  ball  would  float  at  a  great  depth  ;   but  the 
magnitude  of  cohesive  masses,  and  the  abundance  of  them,  may 
be  imagined  such,  that  they  may  be  fast  locked  and  fixed  together, 
in  the  manner  of  field-ice,  at  the  same  time  that  the  weight  of  them 
is  such  as  would  float  them  were  they  loose,  like  an  iceberg, 
with  a  relatively  small  portion  of  the  floating  mass  emergent.    In 
a  word,  a  solid  crust  might  exist,  sustained  by  the  water  in  which 
it  is  immersed,  at  the  same  time  that  the  irregular  and   uneven 
surface  of  the  cohesive  mass  emerges  in  part,  while  other  portions 
are  submerged."* 

28.  Leslie   instituted    some    important    experiments   on    the 
compressibility   of    different   kinds   of    matter,  from   which   he 
drew  very  remarkable  conclusions,  deeply  affecting  the  subject 
under   consideration.     He  computed  that  air  under  the  law  of 
uniform  condensation  would  become  as  dense  as  water  at  the 
depth  of  33J  miles,  and  that  at  a  further  depth  of  163J  miles,  it 
would  acquire  the  density  of  quicksilver.     Water  at  the  depth  of 
93  miles  would  be  compressed  to  half  its  former  bulk  ;  and  at  the 
depth  of  362^  miles  would  be  as  dense  as  quicksilver.     Even 
marble  itself,  subjected  to  its  own  pressure,  would  become  twice 
as  dense  as  before,  at  the  enormous  depth  of  2871  miles.     Air, 

What  would  be  the  density  of  air  compared  with  that  of  water,  suppos- 
ing its  compressibility  uniform,  if  compressed  with  a  force  of  826  atmos- 
pheres ?  (See  Scientific  Class  Book,  pt.  i.  p.  154.) 

How  may  we  conceive  the  crust  of  the  earth  to  be  disposed  in  regard  to 
its  condens'ed  liquid  ingredients? 

At  what  depth  beneath  the  surface  of  the  ocean  would  a  mass  of  air, 
carried  from  the  surface,  have  a  density  equal  to  that  of  water  ? 

At  what  depth  did  Leslie  suppose  that  water  would  have  the  same  den- 
sity as  quicksilver? 

*  On  Fluidity  ;  and  an  Hypothesis  concerning  the  Structure  of  the  Earth. 
Journ.  of  Science,  voL  ix.  pp.  52 — 61. 


308  GEOLOGY. 

however,  from  its  rapid  compressibility,  would  acquire  the  same 
density  with  water,  sooner  than  the  latter  fluid  would  reach  the 
condensation  of  marble.  If  we  calculate  for  a  depth  of  395|. 
miles,  or  about  a  tenth  part  of  the  radius  of  the  earth,  we  shall 
find  that  air  would  attain  the  astonishing  density  of  101960  bil- 
lions ;  while  at  the  «ame  depth  water  would  attain  but  the  density 
of  4.3192,  and  marble  only  that  of  3.8025.  At  the  centre  of  the 
earth  air  would  reach  the  inconceivable  density  denoted  by  7G4, 
with  166  ciphers  annexed;  while  water  would  be  condensed 
3,009,000,  and  marble  acquire  the  density  of  1 19. 

29.  "Such  are  the  prodigious  results  deduced  from  the  law  of 
gravitation,  even  supposing  the  structure  of  the  globe  were 
uniform.  But  if  we  take  into  the  estimate  the  augmented  power 
from  condensation,  the  numbers  would  become  still  more  stupen- 
dous. It  follows,  therefore,  that  if  the  great  body  of  our  earth 
consisted  of  any  such  materials  as  we  are  acquainted  with,  its 
mean  density  would  very  far  surpass  the  limits  assigned  by  the 
most  accurate  investigations.  It  seems,  therefore,  to  follow  con- 
clusively, that  our  planet  must  have  a  very  widely  cavernous 
structure,  and  that  we  tread  on  a  crust  or  shell,  whose  thickness 
bears  but  a  very  small  proportion  to  the  diameter  of  its  sphere. 

30.  Physical  science  can  extend  her  prospects  to  the  farthest  verge 
of  possibilities,  but  chemistry,  even  in  its  present  advanced  stage, 
fails  altogether  in  aiding  inquiry ;  and  the  various  hypothesis 
framed  by  geologists  are  built  with  snch  scanty  and  slender  ma- 
terials, as  to  furnish  no  safe  guidance  through  these  boundless 
speculations.     It   is   evident   that   immense  compression  would 
totally  derange  the  powers  of  elective  attraction,  and  change  the 
whole  form  and  constitution  of  bodies.    When  air  becomes  denser 
than  gold,  it  is  hard  to  conjecture  what  transmutations  this  plastic 
fluid  must  undergo.     The  bowels  of  the  earth  may  contain  sub- 
stances thus  transformed,  bearing  no  longer  any  resemblance  to 
their  aspect  on  its  surface. 

31.  Observations  relative  to  the  temperature  of  the  earth,  and 
the  probable  sources  whence  it  is  derived,  might  be  expected  to 
lead  to  some  reasonable  conclusions  relative  to  its  central  struc- 
ture and  composition.     This  subject  may  be  regarded  as  apper- 
taining  more   directly  to   the   science  of  pyronomics,  than   to 
geology,  and  it  has  accordingly  been  generally  noticed  in  the  pre- 
ceding volume  of  this  work;*    but  is  so  intimately  connected 
with  the  topics  under  discussion,  as  to  require  more  particular 
attention. 

32.  That  the  internal  parts  of  the  earth  are  more  highly  heated 
than  its  surface,  and  that  their  temperature  depends  on  other  causes 

What  change  of  properties  may  we  conceive  to  result  from  the  high  de- 
gree of  compression  arising  from  the  liquid  of  which  the  earth  is  supposed 
to  be  constituted  ? 

*  See  Scientific  Class  Book,  pt.  i.  pp.  280—285. 


INVARIABLE  STRATUM.  309 

than  the  influence  of  the  sun's  rays,  may  naturally  be  inferred 
from  the  phenomena  of  volcanos  and  thermal  springs,  which 
have  in  some  degree  attracted  the  attention  of  philosophers  in 
early  times;  but.  the  doctrine  of  central  heat,  adopted  to  account 
for  these  and  other  analogous  occurrences,  has  recently  derived 
strong  confirmation  fr^u  experiments  and  observations,  instituted 
for  the  express  purpo^  of  ascertaining  how  far  it  is  consistent 
with  the  general  economy  of  nature. 

33.  In  1671,  Cassini,  the  first  distinguished  astronomer  of  that 
name,  noticed  that  in  the  caves  under  the  observatory  at  Paris,  the 
temperature  had  remained  unaltered  during  a  whole  year ;  and  in 
1730,  Lahire  made  a  similar  observation.     Forty  years  later  the 
Count  de  Cassini  first  perceived  the  full  importance  of  this  phe- 
nomenon; and  in  1771,  he  commenced  a  series  of  experiments  for 
the   purpose  of  elucidating  it.      At  length,  on  the  4th  of  July, 
1783,  he,  in  conjunction  with  Lavoisier,  placed  in  the  caves  of 
the  observatory  a  very  sensible  thermometer,  so  arranged  as  to 
show  the   slightest   variations  of  temperature   that   might  take 
place.     It  was  fixed  30.6  yards  below  the  surface,  and  imbedded 
in  sand  ;  and  the  observations  of  Cassini  himself,  with  those  sub- 
sequently made  by  Bouvard  for  thirty-two   years,  showed  that 
during  more  than  half  a  century  the  temperature  of  the  caves  has 
remained    permanent  at  11°.82   of  the  centigrade  thermometer, 
the   slight  oscillations  which  occurred  never  amounting  to  more 
than  25  centiemes  of  a  degree  above  or  below  11°. 82,  and  being 
apparently  owing  to  accidental  causes.     The  mean  annual  tem- 
perature of  the  air  at  Paris  is  only  10°. 6,  so  that  the  constant 
temperature  of  the  earth  there   30.6  yards  beneath  the  surface, 
exceeds  it  by  1°.2  cent.,  or  2°. 16  of  Fahrenheit. 

34.  Hence  it  appears  that  the  depth  corresponding  to  an  aug. 
mentation  of  temperature  amounting  to  1°  is  about  25 1  yards ; 
and  admitting  that  the  temperature  increases  uniformly  with  the 
depth,  the  heat  must  be  equal  to  that  of  boiling  water  at  the  depth 
of  2542  yards  below  Paris.     Observations  thus  exact  and  long 
continued  have  unfortunately  been  made   only  at  the   Parisian 
observatory,  but  from  the  nature  of  the  results  it  may  be  inferred, 
that  this  stability  of  subterranean  temperature,  is  not  an  accidental 
phenomenon,  but  depends  on  general  causes,  and  therefore  it  may 
be  concluded  that  in  all  places,  at  a  given  depth  beneath  the  sur- 
face of  the  earth,  there  is  a  certain  point  at  which  the  temperature 
remains  constantly  the  same,  being  uninfluenced  by  those  causes 
which  may  effect  the  surface. 

What  general  truths  may  we  deduce  from  the  phenomena  of  volcanos 
and  hot  springs  ? 

What  facts  were  observed  by  Cassini  in  regard  to  this  subject? 

What  is  the  temperature  of  the  caves  of  the  Paris  observatory  in  degrees 
Fah.  ?  How  much  variation  is  found  there  in  the  course  of  a  year  ? 

What  is  the  mean  temperature  at  the  surface  of  the  ground  f 

If  the  interior  heat  increases  uniformly,  at  what  depth  below  the  surface 
would  be  found  the  temperature  of  boiling  water  ? 


310  GEOLOGY. 

35.  The  series  of  such  points  of  invariable  temperature  around 
the  globe  may  be  termed  the  invariable  stratum,  at  which  the 
influence  of  all  those  alternations  of  heat  and  cold,  occasional  or 
periodical,  which  might  act  on  the  superior  soil,  would  be  extin- 
guished. This  stratum,  however,  cannot  be  considered  as  forming 
a  regular  curve,  or  maintaining  a  constant^istance  from  the  sur- 
face ;  for  its  depth  and  conformation  musr^Be  affected  by  the  na- 
ture of  the  surface,  as  consisting  of  land  or  water,  and  as  being 
diversified  by  plains,  mountains,  and  valleys,  and  composed  of 
materials  more  or  less  dense  and  compact. 

36.  A  few  observations  only  have  been  made  relative  to  the 
variations  of  temperature  which  take  place  in  the  space  between 
the  surface  and  the  invariable  stratum.     So  far  as  they  go,  how- 
ever, they  tend   to  show  that  the  influence  of  the  solar  heat  pre- 
vails in  the  summer  months,  and  that  of  central  heat  in  the  winter, 
as  might  be  expected.     But  the  most  important  observations  are 
those  which  have  been  made  on  the  temperature  of  the  earth 
below  the  invariable  stratum.     The  prevalence  of  heat  in  mines 
had  been  noticed  arid  variously  accounted  for  by  philosophers,  long 
before  it  was  made  the  subject  of  direct  experiment.     Gensanne 
appears  to  have  first  discovered  that  the  temperature  of  the  earth 
increases  with  the  depth  below  the  surface,  by  means  of  thermo- 
metrical  observations  instituted  in  the  lead  mines  of  Giromagny, 
near  Befort,  in   1740;  and  in   1785,  corresponding  experiments 
were  made  by  Saussure,  in  a  mine  at  Bex,  in  the  canton  of  Berne. 
In  1791,  the  subject  occupied  the  attention  of  Humboldt,  who 
made  an  extensive  and  interesting  series  of  experiments  in  the 
mines  of  Freyberg. 

37.  In  1802,  D'Aubuisson  revived  the  important  investigation, 
and  since  that  time  observations  have  been  multiplied  in  the  prin- 
cipal mines  of  Europe,  in  France,  in  Germany,  and  in  England, 
while  Humboldt,  proceeding  on  his  memorable  scientific  voyage, 
in  1798,  examined  the  temperatures  of  the  mines  of  America  to 
the  depth  of  522  metres. 

38.  M.  Cordier,  in  1827,  published  an  interesting  memoir,  on 
the  temperature  of  the  earth,  (in  Memoires  du  Mustum  d'Histoire 
NaturelleJ)  in  which  he  collected  the  observations  of  others,  to- 
gether with  his  own,  and  having  classed  and  arranged  them,  drew 
from  them  some  interesting  general  conclusions.     He  ascertained 
that  after  making  due  allowance  for  the  heat  in  mines  arising  from 
the  presence  of  miners,  the  combustion  of  lamps,  and  communi- 
cation with  the  atmosphere,  the  following  results  were  established: 

39.  (1.)   Below  the  invariable  stratum,  where  the  oscillations 
of  surface  heat  are  extinguished,  the  temperature  remains  per- 
fectly constant  for  given  depths,  without  any  variation  for  several 

What  general  inference  may  we  derive  from  these  facts  ? 
Who  first  discovered  the  increase  of  temperature  as  we  descend  below 
the  invariable  stratum? 

What  subsequent  investigations  of  this  subject  have  been  made  ? 


CONTRACTION  OF  THE  EARTH.  311 

years.  (2.)  That  in  all  places  where  observations  have  been  made 
below  the  invariable  stratum,  the  temperature  'always  goes  on  in- 
creasing with  the  depth.  (3.)  That  the  ratio  of  the  augmentation 
of  temperature,  in  descending  below  the  invariable  stratum,  is 
different  for  different  places. 

40.  M.  Cordier  considers  that  from  25  to  30  metres'  depth  may 
be  assumed  approximately  as  corresponding  with  an  increase  of 
temperature,  amounting  to  1  centessimal  degree ;  and  therefore  1° 
of  Fahrenheit  may  answer  to  about  15  yards.    On  the  last  suppo- 
sition of  1°  F.  additional  for  every  15  yards  of  vertical  descent, 
it  must  follow  that  at  the  centre  of  the  globe,  supposing  its  mean 
semi-diameter  3956.8  miles  and  the  temperature  to  increase  uni- 
formly, it  would  then  rise  to  464,264°  F.     The  temperature  of 
7000°  F.,  which  would  be  sufficient  for  the  fusion  of  lavas  and 
probably  of  all  kinds  of  rocks  and  metals,  would  be  found  at  the 
depth  of  about  60  miles.     It  is,  however,  uncertain  what  may  be 
the  mean  thickness  of  the  solid    crust  of  the  earth.     Cordier 
imagines  that  it  may  not  exceed  60  miles.     Hence  a  strong  pre- 
sumption arises  in  support  of  the  inference,  that  the  consolidation 
of  the  exterior  crust  is  the  effect  of  a  gradual  cooling. 

41.  If  this  is  the  case  the  consolidation  must  have  commenced 
at  the  surface,  and  proceeded  towards  the  interior;  and  therefore, 
contrary  to  the  received  opinions  of  geologists,  the  primitive  rocks 
are  more  ancient  in  proportion  as  they  are  nearer  the  surface.     It 
follows,  also,  that  the  strata  ought  to  be  arranged  in  the  order  of 
fusibility,  or  nearly  so,  some  allowance  being  made  for  the  inter- 
ruption of  this  order,  owing  to  the  rapidity  of  cooling  at  first,  and 
to  the  influence  of  chemical  affinity  on  the  vast  mass  of  the  globe. 

42.  Another  necessary  consequence  of  the  hypothesis  is,  a  con- 
traction of  the  dimensions  of  the  earth,  through  the  diminution  of 
its  temperature,  causing  subsidence  and  approximation  of  the  ex- 
terior crust,  and  consequent  dislocation  of  its  parts.     This  may 
account  for  the  numerous  cracks  and  fissures,  and  the  irregularity 
of  the  disposition  and  inclination  of  the  superior  strata.     But  the 
subsidence  not  taking  place  regularly,  would  not  produce  a  gene- 
ral, or  very  extensive  change  of  level,  though  it  might  be  suffi- 
cient to   explain    certain   phenomena   otherwise  not  easily  ac- 
counted for :  such  as  the  apparent  secular  decrease  of  the  water 
of  the  Baltic,  and  the  alteration  of  level  of  the  Mediterranean 
observed  on  the  coast  of  Egypt. 

43.  The  most  important  effect,  however,  of  the  contraction  of 

What  three  general  conclusions  did  Cordier  derive  from  his  investiga- 
tions ? 

At  what  depth  might  we  probably  find  the  temperature  sufficient  to 
maintain  the  metallic  and  rocky  constituents  of  our  globe  in  a  slate  ol' 
fusion  ? 

Where  must  the  consolidation  of  the  globe  have  commenced  on  the  sup- 
position of  its  having  been  once  in  a  state  of  igneous  fusion  ? 

What  consequence  in  regard  to  the  bulk  of  the  globe  must  arise  from 
the  gradual  cooling  of  its  surface  ? 


312  GEOLOGY. 

the  bulk  of  the  earth,  is  an  acceleration  of  its  rotatory  motion. 
For  such  is  the  mechanical  relation  between  the  dimensions  of 
the  earth  and  its  period  of  rotation,  that  if  it  undergoes  contrac- 
tion of  volume,  the  rotatory  motion  must  be  accelerated  ;  whence 
increase  of  centrifugal  force,  causing  the  level  of  the  ocean  to  be 
raised  a  little  between  the  tropics,  and  lowered  in  the  polar  re- 
gions, so  that  the  northern  parts  of  Europe  and  Asia  would  be 
gradually  elevated  above  their  former  level  with  respect  to  the 
sea.*  In  this  way  the  numerous  islands  of  the  Pacific  Ocean 
may  be  supposed  to  be  the  summits  of  mountains  belonging  to  a 
portion  of  submerged  continent. 

44.  The  same  relation  also  affords  the  means  of  measuring  the 
secular  contraction,  for  the  length  of  the  day  is  an  astronomical 
element  of  such  importance  that  the  slightest  variation  would  be 
immediately  detected.    But  observations  sufficiently  accurate  ren- 
der it  certain,  that  since  the  time  of  Hipparchus,  or  during  the 
last  twenty  centuries,  the  length  of  the  day  has  not  varied  by  •%%-§ 
of  a  second.    Hence  it  necessarily  follows,  that  if  the  contraction 
is  proceeding,  it  must  be  at  a  rate  almost  infinitely  slow.     The 
amount  of  contraction,  however,  cannot  safely  be  taken  as  a  mea- 
sure of  the  loss  of  temperature.     The  cooling  takes  place  under 
circumstances  very  different  from  those  in  which  bodies  are  placed 
when  exposed  to  the  free  action  of  the  atmosphere,  and  the  ordi- 
nary laws  of  contraction  must  be  greatly  modified  by  the  enor- 
mous pressure  at  the  depth  of  twenty  leagues  beneath  the  surface. 

45.  It  has  been  found  that  the  temperature  of  springs,  as  they 
issue  from  the  earth,  varies  but  inconsiderably  at  different  seasons 
of  the  year ;  and  that  in  our  hemisphere  they  attain  their  highest 
degree  of  heat  in  general  about  the  month  of  September,  and  their 
lowest  towards  March,  the  difference  of  the  two  extremes  being 
from  1°  to  2°  centig.     From  a  table  of  the  mean  temperature  of 
springs  in  different  parts  of  the  world  compared  with  that  of  the 
air  at  the  surface  of  the  soil,  collected  from  the  experiments  of 
different  observers,  by  M.  Pouillet,  it  appears  that  in  the  torrid 
zone,  the  mean  temperature  of  the  air  is  in  general  somewhat 
lower  than  that  of  springs  ;  but  in  the  temperate  zone  the  contrary 
appearances  take  place  ;  the  springs  are  warmer  than  the  air,  their 
excess  of  temperature  usually  increasing  with  the  latitude,  so  that 
at  60  or  70  degrees,  from  the  accurate  observations  of  Wahlen- 

What  effect  on  the  time  of  a  diurnal  revolution  must  the  contraction  of 
the  earth  produce  ? 

What  does  astronomy  teach  in  regard  to  the  length  of  our  present  days 
compared  with  those  of  2000  years  ago  ? 

How  is  the  contraction  of  bulk  in  the  earth  probably  effected  by  the 
present  circumstances  of  its  crust  ? 

How  is  the  temperature  of  springs  found  to  vary  from  that  of  the  air  in 
the  torrid  zone  ?  How  in  the  temperate  zones  ? 

*  See  Scientific  Class  -Book,  pt.  i.  p.  57,  Nos.  103  and  104  of  Mechanics, 
for  the  manner  of  estimating  centrifugal  force,  and  observations  on  the 
consequences  of  its  overcoming  the  force  of  gravitation. 


HOT  SPRINGS  OF  ICELAND.  313 

berg,  it  may  be  concluded  that  their  temperature  is  from  3°  to  4° 
centig.  above  that  of  the  air. 

46.  Investigations  of  the  heat  of  Artesian  wells,*  have  brought 
to  light  some  important  results  relative  to  the  internal  tempera- 
ture of  the  earth.     M.  Arago  collected  observations  whence  it 
appeared  that  the  greater  the  depth  of  such  wells,  the  higher  is 
the  temperature  of  the  waters  that  flow  from  them.     M.  Fleuriau 
de  Bellevue  found  that  the  temperature  of  the  water  at  the  bottom 
of  an  Artesian  well,  by  the  sea  side,  near  Rochelle,  316  feet  deep, 
was  16°.25  centig. ;  and  the  boring  being  afterwards  continued 
to  the  depth  of  369.5  feet,  the  temperature  at  the  bottom  was 
found  to  be  18°.  12  centig.,  the  mean  surface  temperature  of  the 
country  being  11°.287  centig.f 

47.  Though  there  are  various  circumstances  that  might  occur  to 
modify  the  temperature  of  springs,  yet  it  must  be  inferred  from 
the  preceding  observations  that  some  springs  display  degrees  of 
heat  greater  than  could  be  supposed  to  be  caused  by  the  influence 
of  the  rays  of  the  sun  propagated  through  the  superficial  strata  of 
the  earth.     This  also  still  more  evidently  appears  from  the  tem- 
perature of  thermal  waters,  sometimes  approaching  to  the  boiling 
point. 

48.  The  source  of  heat  in  springs  or  fountains  of  this  kind  has 
been  the  subject"  of  much  controversy.     Connected  as  they  fre- 
quently are  with  volcanos,  their  temperature  may  naturally  be 
imputed  to  volcanic  agency ;  arid  when  hot  springs  are  found  tra- 
versing cracks  in  strata  not  volcanic,  attempts  have  been  made  to 
account  for  the  phenomena  by  chemical  combinations  at  incon- 
siderable depths ;  but  the  salts  usually  found  dissolved  in  these 
waters  do  not  afford  support  to  this  theory,  and  Berzelius  has 
shown  it  to  be  untenable  with  respect  to  the  Carlsbad  waters.:}: 
Numerous  instances  occur  of  the  existence  of  thermal  springs  in 
tracts  of  country  distant  from  any  open  or  extinct  volcanos.     It 
may,  however,  be  alleged  that  they  may  possibly  communicate 
with  some  deeply-seated  foci  of  volcanic  agency;  yet  admitting 
such  communication  it  would  only  tend  to  prove  that  volcanos, 
as  well  as  thermal  fountains,  owe  their  origin  to  central  heat. 

49.  Among  the  hot  springs  obviously  connected  with  volcanos 
are.  the  Geysers  in  Iceland,  the  phenomena  of  which  deserve  to 
be  noticed,  as  the  extraordinary  effects  exhibited  serve  in  some 

What  light  is  thrown  upon  this  subject  by  the  examination  of  Artesian 
weHs  ? 

What  is  sometimes  found  to  be  the  temperature  of  hot  springs  ? 
What  theories  have  been  formed  to  account  for  the  heat  of  thermal  waters? 
To  what  common  cause  may  volcanos  and  hot  springs  be  referred  ? 

*  For  an  account  of  the  nature  of  Artesian  wells,  see  Treatise  on  Hy- 
drostatics, Scientific  Class  Book,  pt.  i.  p.  144. 

t  De  la  Beche's  Geological  Manual,  3d  ed.,  1833, 8vo.,p.  13;  from  Journ. 
de  Geologie,  torn.  i. 

|  Id.  p.l7. 

2D 


314 


GEOLOGY. 


degree  to  indicate  the  extent  and  magnitude  of  the  power  by  which 
they  are  produced. 

"These  intermittent  hot  springs  rise  from  a  large  tract,  covered 
to  a  considerable  depth  by  a  stream  of  lava,  and  where  thermal 
water  and  apertures  evolving  steam  are  very  common.  The  Great 
Geyser  rises  out  of  a  spacious  basin,  at  the  summit  of  a  circular 
mound,  composed  of  siliceous  incrustations,  deposited  from  the 
spray  of  its  waters.  The  diameter  of  the  basin  or  crater  in  one 

direction  is  56  feet,  and 
46  in  another.  In  the 
centre  is  a  pipe  78  feet 
in  perpendicular  depth, 
and  from  8  to  10  feet  in 
diameter,  but  gradual- 
ly widening  as  it  opens 
into  the  basin.  The 
inside  of  the  basin  is 
whitish,  consisting  of 
a  siliceous  incrusta- 
tion, and  perfectly 
smooth,  ajs  are  two 
small  channels  on  the 
sides  of  the  mound, 
down  which  the  water 
makes  its  escape  when 
filled  to  the  margin. 
The  circular  basin  is 
sometimes  empty,  but 
is  usually  filled  with 
beautifully  transparent 
water  in  a  state  of 
ebullition. 

50.  During  the  rise  of  the  boiling  water  up  the  pipe,  especially 
when  the  ebullition  is  most  violent,  and  when  the  water  flows  over 
or  is  thrown  up  in  jets,  subterranean  noises  are  heard,  like  the  dis- 
tant firing  of  cannon,  and  the  earth  is  slightly  shaken.  The  sound 
then  increases,  and  the  motion  becomes  more  violent,  until  at  length 
a  column  of  water  is  thrown  up  perpendicularly  with  loud  explo- 
sions, to  the  height  of  100  or  200  feet.  After  playing  for  a  time 
like  an  artificial  fountain,  and  giving  off  great  clouds  of  vapour, 
the  pipe  is  evacuated,  and  a  column  of  steam  then  rushes  up  with 
amazing  force  and  a  thundering  noise,  after  which  the  eruption 
terminates.  If  stones  are  thrown  into  the  crater  they  are  ejected 

What  remarkable  instance  supports  the  theory  of  a  volcanic  cause  for 
hot  springs  ? 

Describe  the  Great  Geyser  ? 

What  is  the  appearance  of  the  pipe  or  cavity  whence  the  water  is  pro- 
tected ? 

In  what  manner  does  the  projection  of  water  from  the  Geyser  take  place? 

What  succeeds  to  the  column  of  water  in  this  fountain  ? 


TEMPERATURE  OF  THE  ATMOSPHERE.  315 

instantly,  and  such  is  the  explosive  force,  that  very  hard  rocks  are 
sometimes  shivered  into  small  pieces.  Henderson  found  that  by 
throwing  a  great  quantity  of  large  stones  into  the  pipe  of  Strocke, 
one  of  the  Geysers,  he  could  bring  on  an  eruption  in  a  few  minutes.* 
The  fragments  of  stone,  as  well  as  the  boiling  water,  were  thrown 
in  that  case  to  a  much  greater  height  than  usual.  After  the  water 
had  been  ejected,  a  column  of  steam  continued  to  rush  up,  with  a 
deafening  roar,  for  nearly  an  hour  ;  but  the  Geyser,  as  if  exhausted 
by  this  effort,  did  not  give  symptoms  of  a  fresh  eruption  when  its 
usual  interval  of  rest  had  elapsed. "f 

51.  Sir  George  Mackenzie  describes  the  continual  discharge  of 
water  and  steam  from  the  Great  Geyser,  during  its  period  of  excite 
ment,  as  resembling  the  distant  firing  of  artillery  from  a  ship  at 
sea ;  and  he  estimates  the  height  of  the  jet  as  being  at  least  90  feet. 
The  temperature  of  the  water  in  the  pipe,  when  sufficiently  high 
for  observation,  was  found  to  be  209°  Fahrenheit. £     There  are 
several  other  alternating  hot  springs  in  Iceland,  one  of  which,  called 
the  New  Geyser,  formerly  an  insignificant  fountain,  now  explodes 
like  that  already  described  ;   but  most  of  these  springs  are  of 
inferior  magnitude  to  the  Geysers. 

52.  The  distribution  of  heat  in  large  masses  of  water,  as  lakes 
and  seas,  is  much  more  uniform  than  in  the  solid  strata.  This  fact, 
ascertained  by  Saussure,  by  means  of  experiments  on  the  lakes  of 
Switzerland  between  1777  and  1784,  may  be  regarded  as  depend- 
ing on  that  property  of  water,  in  virtue  of  which  it  acquires  its 
greatest  density,  a  few  degrees  above  the  freezing  point.     More 
extensive  observations,  however,    have   shown,   that   while   the 
temperature  of  water  varies  but  little  at  different  depths  in  the 
temperate  zone,  it  increases  with  the  depth  in  the  polar  seas ;  and 
this  augmentation  of  temperature  in  descending,  may  reasonably 
be  supposed  to  depend  on  the  influence  of  central  heat. 

53.  The  temperature  of  the  atmosphere,  like  that  of  the  sea  in 
the  equatorial  regions,  decreases  generally  with  the  distance  from 
the  surface.    And  hence  extreme  cold  prevails  at  a  great  elevation. 
The  tops  of  high  mountains  in  the  torrid  zone  are  covered  with 
perpetual  snow,  and  M.  Gay  Lussac,  in  his  famous  aeronautic  ex- 
pedition, having  ascended  about  a  league  and  a  half  above  the  city 
of  Paris,  experienced  a  depression  of  temperature  12°  centig.  below 
the  freezing  point.     At  greater  heights  the  cold  would  become 
utterly  insupportable.  These  circumstances  depend  chiefly  on  the 

What  is  the  effect  of  throwing  heavy  bodies  into  this  spring  ? 
What  temperature  has  the  water  in  this  case  ? 

What  is  the  relative  uniformity  of  temperature  in  the  solid  and  the  li- 
quid parts  of  the  globe  ? 

How  do  waters  vary  in  different  latitudes  ? 

What  is  the  comparative  temperature  of  air  in  high  and  in  low  situations  1 

*  Journal  of  a  Residence  in  Iceland,  p.  74. 

t  Lyell's  Principles  of  Geology,  vol.  ii.  pp.  307—309. 

|  Mackenzie's  Travels  in  Iceland. 


316  GEOLOGY. 

absence  of  reflecting  bodies  in  the  higher  regions,  and  the  rarity 
of  the  air,  which  affords  a  free  passage  to  the  solar  rays,  deriving 
from  them  but  an  inconsiderable  augmentation  of  temperature, 

54.  However,  though   the  cold   appears  to  increase  with  the 
height  throughout  the  extent  of  the  earth's  atmosphere,  it  is  proba- 
ble that  there  is  a  limit  in  space  beyond  which  the  temperature 
cannot  descend.  The  earth  and  the  other  planets  may  be  regarded 
as  moving  within  a  medium  of  uniform  temperature,  such  as  would 
exist  within  the  sphere  of  uranus,  if  the  sun  and  all  the  planetary 
bodies  were  removed.     That  such  a  temperature  occurs  in  the 
regions  beyond  the  atmosphere,  may  be  inferred  from  various  con- 
siderations. The  innumerable  stars  scattered  through  the  heavens, 
glittering  with  light  as  we  behold  them,  cannot  be  imagined  to  be 
destitute  of  heat,  and  how  feeble  soever  their  influence,  in  con- 
sequence of  their  distance,  they  must  produce  some  effect  on  bodies 
in  surrounding  space. 

55.  Admitting,  then,  that  there  is  an  elastic  medium  beyond  the 
atmosphere  of  the  earth,  as  seems  to  be  proved  by  observations  on 
the  periodic  revolutions  of  Encke's  comet,*  it  must  have  a  certain 
capacity  for  heat,  like  all  other  matter.  But  whether  the  temperature 
of  the  planetary  spaces  be  caused  by  radiation  from  the  stars,  or  be 
regarded  as   essentially  belonging   to   the   elastic   medium,   the 
mathematical  investigation  of  the  state  of  the  surface  of  the  earth 
proves  that  there  must  exist  a  fundamental  temperature,  indepen- 
dent of  the  sun  or  any  sources  of  internal  heat ;  for  otherwise,  the 
superficial  temperature  would  be  very  different,  and  its  decrease 
from  the  equator  to  the  poles  incomparably  greater  than  it  is  in 
reality. 

56.  If  the  earth  revolved  in  a  medium  absolutely  destitute  of 
heat,  the  slightest  variations  in  the  sun's  distance  would  occasion 

What  may  we  suppose  to  be  the  conditions  of  the  celestial  spaces  in  re- 
gard to  changes  of  temperature  ? 

In  what  medium  do  the  planets  and  comets  probably  move  ? 
How  is  the  existence  of  such  a  medium  proved  ? 

*  The  comet  distinguished  by  the  name  of  the  German  astronomer 
Encke,  who  first  ascertained  that  it  had  a  comparatively  short  period  of 
revolution,  appears  to  be  gradually  approaching  nearer  and  nearer  to  the 
sun  in  each  successive  revolution,  whence  it  follows  that  it  must  move  in 
a  resisting  medium.  Encke  stated  (in  the  Berlin  Ephemeris,  1823)  as  the 
result  of  his  observations,  that  the  periodic  time  of  this  comet  was  shorter 
than  that  deduced  from  earlier  investigations.  Calculations  were  subse- 
quently made  as  to  the  effect  of  perturbations  of  the  comet  produced  by 
its  approach  to  the  planet  Jupiter,  after  making  allowance  for  which,  how- 
ever, it  was  found  that  the  diminution  of  its  orbit  could  only  be  accounted 
for  by  the  existence  of  a  resisting  medium.  "  The  magnitude  of  the  re- 
sistance is  such,  as  to  dimmish  the  periodic  time  about  l-10,000lh  of  the 
whole  at  each  revolution,  a  quantity  so  large  that  there  can  be  no  mistake 
about  its  existence.  The  history  of  this  discovery  is  undoubtedly  one  of 
the  most  curious  that  modern  astronomy  has  presented." — Prof.  Airy  on 
Astronomy,  in  Rep.  of  Brit.  Assoc.for  1832,  p.  163.  See  also  Whewell's 
Astronomy  and  General  Physics,  Bridgwater  Tr.,  b.  3,  ch.  iv. 


CENTRAL  TEMPERATURE  OF  THE  EARTH.       317 

sensible  changes  of  temperature,  and  the  diurnal  alterations  would 
be  fatal  to  organic  life.  These  effects  must  be  in  some  degree  modi- 
fied by  the  presence  of  the  atmosphere,  yet  the  comparatively 
small  variations  of  temperature  which  actually  take  place  are  in- 
compatible with  the  existence  of  a  degree  of  cold  in  the  planetary 
regions,  much  beyond  the  freezing  point  of  mercury.  On  com- 
puting the  amount  of  temperature  which  the  medium  without  the 
atmosphere  must  possess,  to  account  for  the  existing  thermometri- 
cal  state  of  the  earth's  surface,  Baron  Fourier  found  that  the 
phenomena  are  such  as  would  result  from  the  supposition  that  the 
celestial  spaces  have  a  temperature  equal  to  50°  centig.,  or  58° 
Fahrenheit  below  zero.  It  should  be  remarked,  that  this  theory 
has  been  to  a  certain  extent  confirmed  by  the  researches  of  M. 
Svanberg,  a  Swedish  philosopher,  who  having  investigated  the 
temperature  of  the  planetary  spaces  upon  a  principal  different  from 
that  adopted  by  Fourier,  arrived  at  nearly  the  same  conclusion.* 
57.  All  the  phenomena  of  temperature,  as  respects  the  solid 
parts  of  the  earth,  the  waters,  and  the  atmosphere,  seem  consistent 
with  the  hypothesis  of  central  heat;  but  there  is  an  apparent  ob- 
jection which  demands  some  notice.  It  might  be  imagined  that 
the  intense  heat  of  the  nucleus  of  the  earth  is  incompatible  with 
the  present  temperature  of  its  surface.  But  it  has  been  demon- 
strated from  mathematical  investigation  of  the  laws  which  regulate 
the  propagation  of  heat,  that  there  may  exist,  not  merely  at  the 
centre  of  the  earth,  but  even  at  comparatively  small  depths  below 
the  surface,  a  temperature  sufficient  to  fuse  the  most  refractory 
substances  with  which  we  are  acquainted. f 

What  consideration  proves  the  existence  of  a  uniform  temperature  in  the 
planetary  spaces  ?  What  would  be  the  effect  of  diurnal  changes  of  tem- 
perature if  the  earth  were  in  a  medium  absolutely  cold  ? 

What  actual  temperature  did  the  computations  of  Fourier  assign  to  the 
spaces  beyond  our  atmosphere  ? 

What  objection  has  been  raised  to  the  theory  of  central  heat  ? 

*  Foreign  Review,  vol.  viii.  pp.  311,  312 ;  Pouillet  Elemens  de  Phys.  Ex. 
et  de  Meterologie,  torn.  ii.  pp.  663 — 665.  6% — 700  ;  Berzelius's  Annual  Re- 
port to  the  Academy  of  Sciences  at  Stockholm  for  1829 ;  Edinb.  Journ.  of 
Science,  vol.  hi.,  New  Series. 

t  "  The  following  are  the  most  remarkable  deductions  made  by  Fourier 
from  the  analytical  investigation  of  the  hypothesis  of  an  internal  heat. 
Supposing  the  conducting  power  of  the  materials  of  the  earth,  to  equal 
that  of  iron,  and  that  the  temperature  increases  by  l-30th  ot  a  centesimal 
degree  for  every  metre  of  vertical  descent,  (about  l-18th  of  a  degree  of 
Fahrenheit  for  every  yard,)  which  is  the  rate  indicated  by  observation, 
thfe  enormous  heat  accumulated  in  the  interior  would  cause  an  augument- 
ation  of  temperature  at  the  surface,  amounting  only  to  a  quarter  of  a  de- 
gree above  that  which  is  due  to  the  heating  effects  of  the  sun.  This  small 
addition  to  the  effects  of  solar  heat  is  in  proportion  to  the  conducting 
powers  of  tbe  envelope,  all  other  circumstances  remaining  the  same  ;  con- 
sequently as  the  conductibility  of  the  superficial  materials  of  the  earth  is 
considerably  less  than  that  of  iron,  the  augumentation  of  temperature  just 
mentioned  is  estimated  too  high,  and  probably  does  not  exceed  l-30th  of  a 
centesimal  degree.  Hence  the  effects  of  a  central  heat  are  altogether  in- 
sensible at  the  surface." — Foreign  Review,  u.  a.  p.  313. 
2D2 


318  GEOLOGY. 

58.  The  admission  of  an  original  state  of  igneous  fusion  of 
the  materials  composing  the  terrestrial  globe,  their  gradual  cooling 
from  the  surface  towards  the  interior,  and  the  existence  during  a 
very  protracted  period  of  a  central  nucleus  still  intensely  heated, 
may  be  granted  as  probable — not  only  as  being  supported  by  the 
evidence  derived  from  the  researches  concerning  the  temperature 
of  mines,  springs,  and  waters  in  general,  in  various  parts  of  the 
world,  of  which  some  account  has  been  given — but  also  because 
it  will  account  for  the  structure  and  figure  of  the  earth,  as  being  a 
spheroid  of  revolution,  constituting  a  mass  of  matter,  the  density 
of  which  increases  towards  the  centre. 

59.  To  the  same  cause  may  be  attributed  the  existence  of  vol- 
canos  widely  distributed  over  the  globe,  and  manifesting  a  com- 
mon and  deeply-seated   origin;   and  the  occurrence   of  thermal 
springs  having  their  sources  far  beneath  the  surface,  and  sometimes 
appearing  at  a  distance  from  the  craters  of  volcanos,  though 
probably  in  general  more  or  less  connected  with  them  in  the  bowels 
of  the  earth.     To  the  evidence  for  the  existence  of  central  heat 
derived  from  these  considerations,  may  be  added  the  proofs,  that 
in  the  temperate  and  frigid  zones  of  the  earth  a  temperature  pre- 
vailed, at  a  very  remote  period,  equal  if  not  superior  to  the  utmost 
beat  of  the  torrid  zone  at  present;  and  such  as  was  adapted  to 
call  into  existence^  profusion  of  organic  beings,  both  in  the  animal 
and  vegetable  kingdoms,  on  a  most  gigantic  scale. 

60.  "  As  there  is  great  difficulty  of  conceiving  any  other  than 
the  igneous  fluidity  of  our  planet  previous  to  the  consolidation 
of  its  surface,  and  as  fluidity  seems  essential  to  the  figure  of  the 
earth,  it  has  been  suggested  that  the  earliest  transition   from  a 
liquid  to  a  solid  state,  consequent  on  the  radiation  of  heat,  would 
take  place  at  the  equator,  and  that  masses  of  the  solidified  crust 
would  float  upon  the  incandescent  fluid  beneath.*    The  fluid  mass 
would  necessarily  be  influenced  by  tides  :  therefore  so  long  as  the 
solidified  crust  was  too  thin  to  resist  the  effects  of  this  cause,  it 
would  be  broken  up  into  fragments,  the  precursors  of  those  of 
which  the  solid  surface  of  our  globe  is  every  where  composed." 

61.  When  the  surface  of  England  is  minutely  examined,  there 
is  found  scarcely  any  area  of  eight  or  ten  square  miles  in  extent 
which  has  not  been  fractured  or  broken  up  into  minor  portions,  by 
causes,  that  have  acted  at  various  geological  epochs.    What  is  thus 
true  of  England  is  found  to  be  also  generally  true  of  the  whole  sur- 

VVhat  facts,  besides  the  observed  temperatures  of  the  earth,  favour  the 
supposition  of  igneous  fusion  at  the  centre? 

What  was  formerly  the  temperature  of  the  present  northern  frigid  zone  ? 

What  proves  such  to  have  been  its  state  in  regard  to  heat? 

What  part  of  the  earth's  surface  may  we  presume  to  have  been  first  so- 
lid, fied  ? 

What  appear  to  be  the  relative  ages  of  the  fractured  portions  of  the 
earth's  surface  ? 

*  Croizet  et  Jobert  Recherches  sur  les  Ossemenes  Fossiles  de  Dep.  du 
Puy  de-Dome.  1828. 


SUPERFICIAL  STRUCTURE  OF  THE  EARTH.  319 

face  of  our  continents  and  islands,  when  examined  with  the  neces- 
sary attention.  Sometimes  a  more  modern  deposit  may  mask  the 
surface  broken  into  fragments,  the  former  not  having  been  yet  acted 
on  by  disrupting  forces ;  but  when  rocks,  on  which  such  deposits 
rest,  are  exposed  by  denudation  of  any  kind,  either  in  ravines,  or 
over  a  certain  extent  of  horizontal  area,  they  will  be  found 
fractured. 

62.  There  must  have  been  inequalities  in  the  earth's  surface 
from  its  earliest  consolidation.     The  radiation  of  heat,  and  the  ne- 
cessity of  the  exterior  solid  crust  conforming  to  the  fluid  surface 
beneath,  could  not  have  done  otherwise  than  produce  them.  Hence 
M.  Elie  de  Beaumont's  theory  of  the  elevation  ol  mountain  chains, 
which  rests  on  the   necessity  of  the   earth's   crust   continually 
diminishing  its  capacity,  notwithstanding  the  nearly  rigorous  con- 
stancy of  its  temperature,  in  order  that  it  should  not  cease  to  em- 
brace its  internal  mass  exactly,  the  temperature  of  which  diminishes 
sensibly,  while  the  refrigeration  of  the  surface  is  now  nearly  in- 
sensible.* 

Influence  of  Existing  Causes  on  the  Structure  and  Conformation  of 
the  Surface  of  the  Earth. 

63.  The  terrestrial  globe,  the  general  dimensions  of  which  have 
been  already  stated,  is  composed  of  various  kinds  of  matter  sub- 
sisting in  the  solid  or  fluid  state,  and  encompassed  by  an  atmos- 
phere of  elastic  or  gaseous  fluids,  of  uncertain  extent,  but  gradually 
decreasing  in  density  as  it  recedes  from  the  earth's  surface.     The 
superficial  distribution  of  land  and  water  is  extremely  irregular, 
and  the  area  covered  by  the  latter  far  exceeds  the  space  occupied 
by  the  former,  which  probably  does  not  amount  to  more  than  a 
fourth  part  of  the  entire  surface.     A  larger  portion  of  dry  land  is 
found  in  the  northern  hemisphere  than  in  the  southern,  that  part 
of  the  globe  which  is  to  the  south  of  the  equator  being  chiefly 
covered  by  the  sea,  while  to  the  north  of  the  line  sea  and  land  are 
more  equally  distributed. 

64.  The  surface  of  the  earth  exhibits  abundance  of  obvious 
irregularities,  or  elevations  and  depressions,  the  land  rising  into 
mountains  in  some  places,  and  sinking  in  others  into  glens  and 
valleys  ;  and  in  the  parts  under  the  sea  similar  inequalities  of  level 
are  found  to  exist.    But  though  this  diversity  of  configuration  ap- 
pears sufficiently  striking  when  viewed  in  detail,  yet  a  little  con- 
sideration will  evince  that  these  irregularities  are  quite  unimport- 

Why  is  this  circumstance  not  generally  obvious  ? 
What  is  Beaumont's  view  of  the  origin  of  mountains  ? 
What  is  the  relative  area  of  land  and  water  on  the  surface  of  the  globe  ? 
What  is  the  form  of  the  bottom  of  the  ocean  ? 

How  are  the  irregularities  of  the  earth's  surface  in  comparison  with  its 
whole  diameter? 

*  De  la  Beche's  Geological  Researches,  chap.  iii.  pp.  45,  46. 


320  GEOLOGY. 

ant  when  estimated  with  reference  to  the  magnitude  of  the  ter- 
restrial spheroid. 

65.  The  loftiest  peaks  in  the  world  are  supposed  to  be  those  of 
Dwalagiri  and  Chandradabani,  in  the  Himalaya  range  of  mountains 
north  of  Hindostan,  said  to  be  about  five  miles  above  the  level  of 
the  sea;  and  on  the  opposite  surface  of  the  globe  are  the  summits 
of  Chimborazo,  Illimani,  and  Sorata,  in  the  ridge  of  the  Andes, 
the  height  of  which  is  probably  somewhat  more  than  four  miles 
above  the  sea.    The  depth  of  the  ocean  beneath  its  common  level, 
it  is  manifest,  can  only  be  calculated  conjecturally,  beyond  those 
points  which  can  be  fathomed  with  the  sounding  line;  but  from 
calculations  founded  on  astronomical  data,  Laplace  inferred  that 
its  mean  depth  was  a  small  fraction  of  25  miles,  the  difference  in 
the  diameters  of  the  earth,  owing  to  the  compression  or  flattening 
at  the  poles.*     It  has  been  variously  estimated  at  between  two 
and  three  miles ;  and  it  may  be  reasonably  concluded  that  the  bot- 
toms of  the  lowest  submarine  vallies,  or  cavities  in  the  bed  of  the 
ocean,  do  not  reach  further  beneath  its  surface  than  the  summits 
of  the  loftiest  mountains  extend  above  that  level. 

66.  If,  then,  five  miles  be  assumed  as  the  height  of  the  most 
exalted  protuberances,  and  also  as  to  the  depth  of  lowest  depres- 
sions on  the  solid  surface  of  the  earth,  the  utmost  inequalities  of 
level  cannot  exceed  ten  miles,  which  will  be  little  more  than  ¥-l_ 
part  of  the  diameter  of  the  globe.     But  the  sea  covering  so  large  a 
portion  of  the  exterior  of  the  earth,  causes  the  whole  mass  to  as- 
sume the  form  of  a  nearly  perfect  spheroid,  irregularly  dotted  with 
relatively  minute  points,  the  most  considerable  of  which  protrudes 
about  Tg^o-  of  the  earth's  diameter  above  the  common  level  of  its 
surface.    Hence,  our  planet  viewed  from  the  moon,  must,  like  that 
satellite,  exhibit  a  circular  outline. 

67.  The  uneven  figure  of  the  earth's  surface  has  been  compared 
to  the  little  risings  and  indentations  on  the  rind  of  an  orange,  but 
with  reference  to  the  diameters  of  the  two  bodies,  the  irregularities 

What  is  the  actual  height  of  the  highest  mountains? 
What  is  the  probable  depth  of  the  lowest  ocean  vallies  ? 
How  would  the  earth's  surface  appear  when  viewed  from  the  moon  or 
a  planet  ? 

*  "  On  a  regarde  long-temps  la  profondeur  de  la  mer  comme  incalcula- 
ble, on  la  disait  immense.  II  est  vrai  que  par  rapport  a  nous  elle  est  tres- 
grande,  qu'elle  est  incommensurable  mecaniquement  par  nos  appareils  les 
plus  perfectiones,  et  quoique  1'etendue  des  regions  marines  dont  on  n'a 
pu  trouver  le  fond  soit  tres-vaste,  on  ne  doit  pas  en  conclure  que  ce  fond 
n'existe  point.  L'astronomie  moderne,  aidee  des  grandes  lois  de  la  gravi- 
tation universelle,  nous  a  devoile  ce  mystere,  et  M.  de  Laplace  a  demon- 
tre,  par  1'influence  que  la  lune  et  le  soleil  exercent  sur  notre  planete,  que 
la  profondeur  moyenne  de  la  mer  ne  pouvait  depasser  8000  metres,  (envi- 
ron 4000  toises.)  Ainsi  les  plus  halites  montagnes  s'elevent  au-dessus  de 
la  surface  des  eaux,  a  la  meme  distance  que  les  abimes  de  1'ocean  s'en- 
foncent  dans  1'interieur  de  la  terre." — Resume  d'un  Cours  EUmentaire  de 
Geographic  Physique,  par  J.  V.  F.  Lamouroux,  D.E.S.,  Prof.  d'Hist.  Nat 
a  Caen,  1821,  8vo.  p.  166. 


IRREGULARITIES  OF  THE  EARTH*S  SURFACE.  321 

of  the  latter  exceed  those  of  the  former  beyond  all  proportion ;  for 
if  the  mountains  and  valleys  of  the  earth  were  modelled  according 
to  the  exact  ratios  of  their  respective  heights  and  depths,  on  the 
surface  of  an  artificial  globe  one  foot  in  diameter,  they  would  be 
hardly,  if  at  all,  perceptible. 

68.  The  surface  of  the  earth  both  above  and  beneath  the  level  of 
the  sea  presents  a  considerable  variety  of  conformation  and  arrange- 
ment. The  higher  parts  of  the  land  consist  of  rocks  and  mountains, 
disposed  in  ridges,  like  the  Alps,  the  Pyrenees,  and  the  Andes,  or 
in  detached  peaks  and  headlands,  as  the  Peak  of  Teneriffe,  and  the 
Table  Mountain  at  the  Cape  of  Good  Hope.   Low  lands  may  form 
extensive  plains,  or  wide  sandy  deserts,  and  marshy  tracts,  or  lines 
of  coast  descending  to  the  level  of  the  sea.    Ravines,  hollows,  and 
valleys,  may  occur  at  various  heights,  rivers  sometimes  flowing 
through  them  to  their  termination  in  lakes  and  seas.  As  to  the  form 
of  the  solid  surface  covered  with  water,  some  interesting  circum- 
stances have  been  observed.     There  can  be  no  doubt  but  the  bed  of 
the  ocean  varies  in  level  in  some  measure  like  the  dry  land.   The 
numerous  islands  scattered  through  the  deep  are  obviously  the 
higher  parts  of  submarine  eminences,  those  portions  of  which  that 
are  under  water  sometimes  forming  sloping  banks,  and  sometimes 
abrupt  and  perpendicular  precipices.     The  declivities,  however, 
except  around  coral  islands,  are  not  probably,  in  general,  very 
steep.  t 

69.  "  The  soundings  round  coasts,"  says  Mr.  De  la  Beche, 
"present  us  with  no  lines  which  we  might  consider  to  be  those  of 
valleys,  but  with  extensive  areas,  which  would,  if  raised  above  the 
level  of  the  sea,  form  great  plains,  with  here  and  there  some  minor 
elevations  and  deeper  depressions',  the  latter  generally  in  the  form 
of  basins.    There  are  indeed  some  long  trough-like  cavities  in  the 
North  Seas,  named  the  Silver  Pits,  but  they  present  us  with  nothing 
like  a  system  of  valleys  resembling  those  on  dry  land.  If  the  British 
Islands  were  elevated  one  hundred  fathoms  above  the  level  of  the 
ocean,  and  thus  joined  to  the  continent  of  Europe,  they  would  be 
surrounded  by  an  extensive  area  of  flat  land ;  for  the  fall  from 
the  present  coasts  to  the  new  sea-coast  would  be  generally  so 
gradual  as  to  present  to  the  eye  one  great  plain."*  The  area  thus 
described,  in  which  the  sea  is  in  general  about  one  hundred  fathoms 
in  depth,  is  bounded  on  the  west  and  north-west  by  a  line  inclu- 
ding the  British  islands,  and  passing  round  them  from  the  coast  of 
France  to  that  of  Norway  ;  and  terminating  towards  the  open  sea 
by  a  slope,  sinking  in  a  comparatively  rapid  manner  into  deep 
water. 

How  may  the  slight  irregularities  of  the  earths  surface  be  illustrated  ? 

How  may  we  regard  the  islands  of  the  ocean  ? 

Of  what  form  are  generally  found  the  bottoms  of  seas  in  the  neigbour- 
hood  of  continents  and  islands  ? 

How  is  this  illustrated  in  the  north  sea  and  other  parts  of  the  ocean 
west  of  Europe  ? 

*  Geolog.  Researches,  pp.  189,  190. 


322  GEOLOGY. 

70.  It  is  a  curious  fact,  that  there  are  continental  portions  of  the 
earth's  surface  considerably  below  the  common  level  of  the  ocean. 
MM.  Parrot  and  Engelhart  appear  to  have  made  the  discovery, 
that  the  Caspian  Sea  and  Lake  Aral  are  beneath  the  level  of  the 
Mediterranean  ;  and  M.  de  Humboldt  ascertained  that  this  depres- 
sion extends  to  an  extensive  territory,  about  18,000  square  leagues 
in  surface.     This  tract  forms  an  immense  basin,  the  lowest  part 
of  which  is  occupied  by  the  Caspian  Sea.  The  surface  of  that  sea 
is  334  feet  beneath  the  level  of  the  Mediterranean,  320  feet  below 
the  level  of  the  Black  Sea,  and  that  of  Lake  Aral  203  feet ;  the 
latter,  as  appears  from  the  recent  measurement  of  Captains  Duha- 
mel  and  Anjou,  being  117  feet  above  the  level  of  the  Caspian.* 

71.  As  there  is  abundant  evidence  that  those  parts  of  the  earth 
constituting  the  present  continents  and  islands  have  been  at  some 
period  or  other  covered  by  water,  so  it  may  be  concluded  that  much 
of  the  bed  of  the  sea  was  once  dry  land  ;  and  indeed  large  tracts 
have  been  submerged  with.in  the  period  of  historical  record.     M. 
De  la  Beche  remarks,  that  "dry  land  can  only  be  considered  as  so 
much  of  the  rough  surface  of  our  globe  as  may  happen,  for  the 
time,  to  be  above  the  level  of  the  waters,  beneath  which  it  may  again 
disappear,  as  it  has  done  at  previous  different  periods."f 

General  View  of  the  Present  State  of  the  Surface  of  the  Earth. 

72.  The  exterior  of  the  earth  not  only  exhibits  numerous  varia- 
tions of  level,  but  it  likewise  shows  a  diversity  of  structure  and 
composition.  Independent  of  the  superficial  covering  formed  from 
the  mixture  of  decayed  animal  and  vegetable  bodies  with  sand, 
clay,  and  other  materials,  arising  from  the  disintegration  of  stones 
and  rocks,  and  serving  as  a  nidus  for  the  production  and  support 
of  a  continual  ^succession  of  plants  of  every  kind,  from  mosses, 
fungi,  and  grasses,  to  the  noblest  trees  of  the  forest,  there  are  many 
peculiar  stratified  or  massive  formations,^:  sometimes  extending 

What  curious  fact  did  Parrot  and  Engelhart  discover  respecting  the  in- 
land seas  of  Asia  ? 

How  are  we  to  regard  the  dry  land  of  the  globe  ? 
Of  what  is  the  exterior  crust  of  the  earth  composed 
What  is  meant  by  the  term  formation  ?     (Note.) 

*  Humboldt  Fragmens  de  Geologic  et  Climatologie  Asiatiques,  torn.  i. 
pp.  9.  91.  136. 

t  Geolog.  Manual,  p.  2. 

t  "  In  geognosy  the  \vordformation  either  denotes  the  manner  in  which 
a  rock  has  been  produced,  or  it  designates  an  assemblage  of  mineral  masses 
so  intimately  connected,  that  it  is  supposed  they  were  formed  at  the  same 
epoch,  and  that  they  present  in  the  most  distant  parts  of  the  earth  the  same 
general  relations,  both  of  composition  and  of  situation  with  respect  to  each 
other.  Thus  the  formation  of  obsidian  and  basalt  is  attributed  to  subter- 
ranean fires;  and  it  is  also  said  that  the  formation  of  transition  clay-slate 
contains  Lydian  stone,  chiastolite,  ampelite,  arid  alternating  beds  of  black 
limestone  and  of  porphyry.  The  first  acceptation  of  the  word  is  the  most 
conformable  to  the  genius  of  the  French  language ;  but  it  relates  to  the 


MODIFYING  ACTION  OF  EXISTING  CAUSES.  323 

over  vast  tracts  of  country,  and  sometimes  interrupted,  mixed,  and 
modified,  producing  new  combinations,  and  by  their  various 
arrangements  composing  the  solid  crust  of  the  earth,  commonly 
more  or  less  covered  and  concealed  by  vegetable  mould  and  verdure, 
but  occasionally  by  barren  sands  or  clay,  or  appearing  in  the  form 
of  rugged,  naked,  or  snow-clad  rocks  and  mountains. 

73.  These  formations,  consisting  respectively  of  series  of  rocks 
in  a  certain  order  of  superposition,  have  been  arranged  by  geolo- 
gists in  groups,  distinguished  with  reference  to  the  supposed  time 
or  mode  of  their  production  :  thus  some  are  designated  as  primary, 
secondary,  and  tertiary;   and  some  as  sedimentary  or  volcanic. 
From  examination  of  the  surface  of  the  earth,  it  appears  that  the 
strata  or  masses  of  rocks  composing  formations  and  groups  have 
suffered  numerous  dislocations  and  interruptions,  indicating  local 
and  general  disturbances,  the  investigation  of  the  nature  and  causes 
of  which  may  advantageously  precede  more  full  and  particular 
descriptions  of  the  several  groups,  formations,  and  rocks,  of  which 
the  crust  or  exterior  portion  of  the  terrestrial  globe  is  composed. 

74.  Whatever  may  have  been  the  cause  of  the  original  forma- 
tion of  the  oldest  rocks,  whether  with  the  Wernerians  we  ascribe 
them  to  aqueous  solution  and  crystallization,  or  with  the  Hutto- 
nians  to  igneous  fusion,  their  production  necessarily  infers  a  con- 
currence of  circumstances  no  longer  existing.  The  case  is  different 
with  respect  to  the  superior  strata  composed  of  the  ruins  of  the 
older  rocks,  and  which,  from   their   containing   imbedded  both 
animal  and  vegetable  remains,  must  obviously  have  been  formed 
at  periods  subsequent  to  the  origin  of  organized  beings.     There- 
fore as  the  structure  and  arrangement  of  such  rocks  may  be  sup- 
posed to  have  been  influenced  by  causes  having  some  analogy 
with  the  existing  order  of  things,  an  inquiry  into  the  nature  and 
extent  of  the  changes  now  going  on  upon  the  earth's  surface  may 
be  expected  to  throw  some  light  on  the  geognostic  history  of  those 
formations  which  took  place  long  before  the  human  species  was 
called  into  existence. 

What  is  signified  by  a  group  in  Geology? 

What  different  names  are  given  to  the  respective  groups  of  formations  ? 
What  changes  have  been  produced  in  the  different  formations  ? 
How  do  the  superior  strata  of  the  earth  differ  from  the  inferior  ? 

origin  of  things,  and  to  an  uncertain  science  founded  on  geogonic  hypo- 
theses. The  second  acceptation,  now  generally  received  by  the  French 
mineralogists,  has  been  borrowed  from  the  celebrated  school  of  Werner, 
and  indicates,  not  what  was  supposed  to  have  been,  but  what  now  exists. 
In  the  geognostic  description  of  the  globe,  we  may  distinguish  different 
modes  of  grouping  mineral  substances  as  we  ascend  to  more  general  ideas. 
Rocks  which  alternate  with  each  other,  which  are  found  usually  together, 
and  which  display  the  same  relations  of  position,  constitute  the  same  for- 
mation— the  union  of  several  formations  constitutes  a  geological  series  or 
group,  (terrain ;)  but  the  terms  rocks,  formations,  and  terrains,  are  used  as 
synonymous  in  many  works  on  geognosy." — HumboldCs  Geognostical 
Essay  on  the  Superposition  of  Rocks,  translated  from  the  French.  1823. 
page.  1. 


324  GEOLOGY. 

Influence  of  Mr,  Water,  and  Volcanic  Fire,  on  the  Surface  of  the 
Earth. 

75.  Many  of  the  changes  that  are  affected  on  the  superficial 
portion  of  the  globe,  are  either  directly  or  indirectly  owing  to  the 
operations  of  man  :  the  cutting  down  of  woods  and  forests,  drain- 
ing lakes  and  marshes,  recovering  tracts  of  land  by  embankment 
from  the  sea,  levelling,  mining,  digging  canals,  constructing  roads 
and    causeways,    with   various    other  works   that    result   from 
human  skill  and  industry,  contribute  more  or  less  to  produce  al- 
terations 011  the  face  of  the  earth  ;  but  their  agency  is  either  remote 
and  contingent,  or  comparatively  insignificant,  and  therefore  need 
not  be  particularly  investigated.     It  is  of  more  importance  to 
consider  the  influence  of  the  elements  displayed  on  a  far  more 
extensive  scale  with  regard  either  to  time  or  space,  and   pro- 
ducing correspondent  effects. 

76.  Air,  water,  heat,  and  perhaps  electricity,  sometimes  acting 
slowly  and  gradually  through  long  periods,  may  modify  or  change 
the  form  and  constitution  of  substances  composing  the  solid  crust 
of  the  earth  ;  and  on  other  occasions  display  overpowering  force 
and  violence,  giving  rise  to  storms  and  hurricanes,  tides,  currents, 
torrents,  and  deluges,  earthquakes  and  volcanos,  spreading  deso- 
lation and  ruin  over  wide  tracts  of  land,  breaking  up  and  displac- 
ing existing  strata,  or  covering  them  with  beds  of  new  matter,  re- 
placing valleys  by  mountains,  or  mountains  by  valleys,  and  thus 
producing  strange  metamorphoses   in   the   appearance   of  those 
countries  over  which  their  influence  extends. 

77.  These  powers  of  nature,  however,  are  not  solely  active  in 
works  of  destruction,  their  agency  sometimes  being  productive 
of  new  formations.     Air  and  heat  may  occasionally  operate  in 
this  way,  but  the  formative  effects  of  water  are  more  obvious  and  ex- 
tensive.   Rivers  deposit  sands,  detrital  matter,  and  silt,  filling  up 
lakes,  and  constituting  deltas  on  the  margin  of  the  sea,  or  shoals, 
sandbanks,   and   islands   rising  amidst  its   waves;    lapidescent 
springs   yield   deposits    of  siliceous   earth,    tufa,  travertin,  and 
stalactitic  limestone;  and  the  water  of  the  sea  in  some  manner 
facilitates  the  operations  of  the  little  animals  employed  in  build- 
ing coral  reefs  and  islands. 

78.  The  influence  of  the  atmosphere  in  modifying  the  surface  of 
the  earth,  whether  destructive  or  formative,  may  depend  either  on 
the  chemical  or  the  mechanical  properties  of  the  aerial  fluids  of 
which  it  is  composed.    Air  must  be  a  powerful  chemical  agent,  in 
consequence  of  its  containing  oxygen  and  carbonic  acid.  The  action 

Of  what  importance  are  the  labours  of  man,  considered  as  modifying 
the  surface  of  the  globe  ? 

What  are  some  of  the  active  causes  which  change  the  exterior  condition 
of  the  earth  ? 

What  is  among  the  most  efficient  of  these  causes  ? 

To  what  properties  does  the  air  owe  its  modifying  influence  on  the  crust 
of  the  earth  ? 


EVOLUTIOX  OF  CARBONIC  ACID.  325 

of  oxygen  may  cause  the  disintegration  of  rocks  in  which  metals 
and  metallic  sulphurets  are  included ;  and,  by  its  universal  affi- 
nity for  other  bodies,  it  may  give  rise  to  numerous  decompositions 
and  combinations,  the  modifying  effects  of  which  must  be  alike 
extensive  and  important. 

79.  Carbonic  acid,  which  is  constantly  present  in  the  atmos- 
phere in  a  relatively  small  proportion,  occurs  abundantly  in  cer- 
tain situations,  being  given  off  from  the  surface  of  springs,  or 
issuing  from  fissures  in  the  earth.  It  is  chiefly  evolved  in  coal-pits 
and  in  volcanic  districts.  Among  the  most  noted  natural  labora- 
tories of  carbonic  acid,  is  the  Grotto  del  Cane,  near  Naples,  the  phe- 
nomena of  which  have  often  been  described  :  and  many  others  occur 
in  different  parts  of  the  world.  This  gas  is  disengaged  in  vast 
quantities  from  every  part  of  the  Limagne  d'Auvergne,  in  France, 
where  it  appears  to  have  been  produced  in  equal  abundance  from 
time  immemorial.  This  elastic  fluid  being  invisible,  it  is  only 
observed  in  consequence  of  its  effects,  as  when  an  excavation  is 
made,  in  which  it  accumulates,  and  a  lighted  candle  or  other 
burning  body  introduced  into  it  becomes  extinguished.  There 
are  some  springs  in  this  district,  where  the  water  is  seen  bubbling 
and  boiling  from  the  copious  disengagement  of  this  gas.  It  has 
an  obvious  effect  on  the  vegetation,  many  trees,  as  the  walnut, 
flourishing  more  luxuriantly  than  they  would  otherwise  do  in  the 
same  soil  and  climate,  probably  owing  to  the  rapid  absorption  or 
decomposition  of  carbonic  acid.  This  gas  is  found  in  springs 
issuing  from  granite,  near  Clermont,  as  well  as  from  the  tertiary 
limestones  of  the  Limagne.* 

80.  In  the  environs  of  Pont-Gibaud,  not  far  from  Clermont,  a 
rock  belonging  to  the  gneiss  formation,  in  which  there  are  lead 
mines,  has  been  found  quite  saturated  with  carbonic  acid,  which  is 
continually  given  off  in  the  gaseous  form.  The  carbonates  of  iron, 
lime,  and  manganese,  are  so  dissolved,  that  the  rock  is  rendered  soft, 
and  the  quartz  alone  remains  unattacked.f  Dolomieu  notices  the 
frequent  evolution  of  carbonic  acid  in  the  vicinity  of  Mount  Etna, 
and  especially  near  Paterno.  "  An  immense  quantity  is  disen- 
gaged from  the  surface  of  a  cold  spring  called  Jlcqua  Rossa,  to  the 
water  of  which  it  communicates  a  powerfully  acid  taste,  and 
gives  it  the  appearance  of  ebullition.  This  gas  seems  to  be  pure 
carbonic  acid,  proving  suddenly  fatal  to  animals  that  respire  it, 
many  being  tempted  by  the  freshness  and  limpidity  of  the  water, 
shaded  by  bushes  and  reeds,  to  quench  their  thirst.  Hares  and 

How  is  the  importance  of  carbonic  acid  proved  ? 

In  what  particular  localities  does  it  abound  ? 

What  effect  does  it  produce  on  the  appearance  of  springs? 

What  description  has  been  given  of  the  Acqua  Rossa  ? 

*Le  Coq  Annales  de  1'Auvergne,  torn.  i.  p.  217.     May,  1828. 
t  Lyell's  Prin.  of  Geol.,  vol.  i.  p.  317,  from  Ann.  d'Auvergne.  June,  1829. 
See  also  G.  Poulett  Scrope's  Memoir  on  the  Geology  of  Central  France. 
2  E 


328  GEOLOGY. 

birds  are  often  found  dead  on  the  banks  of  this  spring."*  Similar 
effects  are  stated  by  MM.  Bischof  and  Noggerath  to  be  produced 
by  the  exhalation  of  carbonic  acid  from  the  vicinity  of  the  lake  of 
Laach,  the  quantity  of  which  has  been  estimated  at  600,000  pounds 
a  day. 

81.  In  the  Brohlthal,  on  the  Rhine,  an  old  volcanic  country, 
there  is  a  considerable  evolution  of  carbonic  acid  gas,  which  is 
employed   by  M.  Bischof  in  the  manufacture  of  chemical  pre- 
parations on  a  large  scale. f      Near  Fort  Diadine,  on  the  Eu- 
phrates, in  Armenia,  are  mineral  springs,  impregnated  with  car- 
bonic acid  and  sulphuretted  hydrogen,  two  of  which  are  remark- 
able for  the  deposition  of  large  quantities  of  carbonate  of  lime.    In 
the  environs  of  these  two  springs  the  limestone  contains  much 
native  sulphur,  which  for  a  long  time  was  collected  ;  but,  the 
carbonic  acid  arising  having  suffocated  many  of  the  workmen, 
the  undertaking  was  abandoned.     The  acid   gas   issues   in  this 
place  from  the  bowels  of  the  earth  in  such  great  quantities,  as  to 
fill  the  caverns  and  neglected  excavations,  forming  numerous  strata 
of  livid  vapours.    It  is  sometimes  evolved  with  so  much  rapidity 
through  the  clefts  as  to  produce  a  strong  current  and  a  hissing 
noise.     Small  birds  seeking  refuge  in  these  caverns,  or  coming 
near  the  fissures,  are  suddenly  stifled.^: 

82.  But  perhaps  the  most  extraordinary  phenomenon  of  this 
kind  in  the  world  is  the  Guevo  Upas,  or  Valley  of  Poison,  in  the 
Island  of  Java,  the  deadly  effects  of  which  contributed  in  no  small 
degree  to  give  currency  to  the  fabulous  report  of  the  existence  of 
a  wonderful  tree  called  the  Bohun  Upas,  so  fancifully  described 
by  Dr.  Darwin,  in  his  "  Botanic  Garden."   The  district  in  which 
this  valley  is  situated  was  visited  by  Mr.  A.  Loudon,  who  states 
that  it  is  three  miles  from  Balor,  on  the  road  to  the  Djung.  He  des- 
cribes it  as  about  half  a  mile  in  circumference,  of  an  oval  form, 
from  30  to  35  feet  in  depth,  and  quite  flat  at  the  bottom ;  destitute 
of  vegetation,  being  covered  with  skeletons  of  human  beings,  tigers, 
hogs,   deer,  peacocks,  and  various  sorts  of  birds,  which   have 
perished  by  entering  into  the  atmosphere  of  carbonic  acid,  with 
which  the  lower  part  of  the  valley  is  filled.   There  were  no  visible 
openings  in  the  ground  at  the  bottom,  which  appeared  to  be  of  a 
hard  sandy  substance.     The  sides  of  the  valley  are  covered  with 
trees  and  shrubs  ;  and  it  may  be  concluded  that  the  gas  does  not 
rise  above  18  feet  from  the  bottom,  as  Mr.  L.  and  others  with  him 

What  practical  use  is  sometimes  made  of  carbonic  acid  naturally  de- 
veloped ? 

Describe  the  Valley  of  Poison. 

How  high  does  the  carbonic  acid  of  that  valley  probably  rise  ? 

*  Memoirs  sur  les  Isles  Ponces ;  et  Catalogue  Raisonnee  de  Produits  de 
1'Etna.     Paris,  1788.     p.  364. 

f  De  la  Beche's  Geol.  Man.,  pp.  154,  155. 

t  Boue  Memoires  Geologiques  et  Paleontologiques.  1832.  torn.  i.  p.  281. 


DISINTEGRATION  OF  GRANITE.  327 

descended  to  that  depth,  where  they  experienced  no  difficulty  of 
breathing  or  inconvenience,  except  that  which  arose  from  the 
offensive  odour  of  the  putrifying  bodies  below.*  No  smell  of 
sulphur,  or  traces  of  volcanic  matter  were  observed  ;  but  there 
can  be  no  doubt  but  the  production  of  carbonic  acid  in  this  situa- 
tion is  connected  with  volcanic  influence,  which  extends  through- 
out Java,  and  many  of  the  neighbouring  islands. 

S3.  The  effect  of  carbonic  acid,  as  a  chemical  agent,  both  as 
commonly  present  in  atmospheric  air,  and  as  more  abundantly 
occurring  in  such  localities  as  those  above  described,  must  de- 
pend on  the  nature  of  the  rocks  and  other  bodies  with  which  it 
may  come  into  contact.  It  may  thus  cause  the  decomposition  of 
granite,  gneiss,  and  other  feldspathic  and  micaceous  substances, 
by  combining  with  the  potash,  soda,  or  lithia,  which  enter  into 
their  constitution.  On  the  contrary,  when  it  encounters  lime  or 
magnesia,  it  may  contribute  to  the  production  of  new  rocks. 
"The  disintegration  of  granite  is  a  striking  feature  of  large  dis- 
tricts in  Auvergne,  especially  in  the  neighbourhood  of  Clermont. 
This  decay  was  called  by  Dolomieu,  'la  maladie  du  granite;1  and 
the  rock  may  with  propriety  be  said  to  have  the  ro/,  for  it  crumbles 
to  pieces  in  the  hand.  The  phenomenon  may  without  doubt  be 
ascribed  to  the  continual  disengagement  of  carbonic  acid  gas  from 
numerous  fissures."! 

84.  The  chemical  action  of  carbonic  acid,  as  it  exists  in  the 
usual  state  of  the  atmosphere  near  the  earth's  surface,  though 
much  more  gradual,  and  therefore  less  noticed  than  were  it 
copiously  evolved  from  the  water  or  soil,  as  in  volcanic  countries, 
is  yet  sufficiently  powerful  to  produce  a  manifest  effect  on  the 
structure  of  large  masses  of  granite  and  rocks  of  analogous  com- 
position. In  the  western  parts  of  Great  Britain  where  primitive 
formations  prevail,  granite  masses  not  unfrequently  occur,  which 
from  their  peculiar  forms  received  the  Celtocymric  appellations  of 
logan,  tolmen,  and  kistvaens ;  and  were  by  Dr.  Borlace  and  other 
antiquaries  long  regarded  as  works  of  art  of  Druidical  origin  ;  but 
these  rocking-stones,  rock-basins,  cheese-rings,  and  altars,  are  now 

generally  admitted  to  be  blocks  of  granite,  which  have  acquired 
leir  respective  forms  in  consequence  of  superficial  decomposition 
or  disintegration.  The  manner  in  which  this  takes  place  may  be 
illustrated  by  the  following  figure  of  a  group  of  such  decaying 
rocks,  forming  a  part  of  Great  Staple  Tor,  on  Dartmoor,  in  Devon- 
shire, seen  from  the  south-west,  j: 

On  what  sources  does  the  large  supply  of  this  gas  depend  ? 
To  what  cause  may  the  disintegration  of  granite  be  ascribed  ? 
What  is  the  probable  origin  of  rocking-stones  and  other  detached  masses 
of  granite  I 

*  Journal  of  Geographical  Society,  vol.  ii. 

t  Lyell's  Prin.  of  Geol.r  vol.  i.  p.  317. 

t  From  De  la  Beche's  Geological  Researches. 


328  GEOLOGY. 


85.  M.  De  la  Beche  remarks,  that  it  is  "  more  like  the  remains 
of  some  huge  building  or  battlement,  than  the  effect  of  cleavage 
and  decomposition,  which  it  is."  Granite  is  not  generally  regarded 
as  a  stratified  rock  like  gneiss  and  mica  slate  ;  but  it  is  a  fact  well 
known  to  the  workmen  who  are  employed  in  quarrying  and  cut- 
ting it,  that  it  has  what  they  term  a  grain,  or  that  it  will  split  in 
one  or  two  directions  more  easily  than  in  others.*     This,  doubt- 
less, is  owing  to  the  arrangement  of  the  mineral  bodies  of  which 
it  is  composed,  and  especially  the  feldspar,  the  decomposition  of 
which  must  essentially  aid  the  process  of  disintegration,  and  de- 
termine in  a  great  degree  the  direction  in  which  it  takes  place. 

86.  There  are  other  gases  which  are  copiously  evolved  in  some 
.situations,  and  particularly  in  the  vicinity  of  volcanos.    Dolomieu 
states,  that  he  ascertained  the  presence  of  sulphurous  acid,  mu- 
riatic acid,  hepatic  gas  or  sulphuretted  hydrogen,  phlogisticated 
or  nitrogen  gas,  and  inflammable  air  or  hydrogen,  as  well  as  car- 
bonic acid,  in  the  exhalations  from  the  surface  around  Mount 
Etna  ;f  and  other  observers  have  noticed  the  occurrence  of  chlorine 
gas.  But  the  most  abundant  of  the  spontaneously  produced  gases, 
next  to  carbonic  acid,  probably  is  carburetted  hydrogen,  well  known 
as  an  agent  of  destruction  in  coal-mines.     It  is  likewise  some- 
times emitted  from  the  surface  of  the  soil,  or  of  springs  and  wells. 

87.  The  country  around  Baku,  on  the  western  shore  of  the 
Caspian  Sea,  is  remarkable  for  its  numerous  mud  volcanos  and 
fountains  of  naphtha,  the  soil  apparently  being  every  where  im- 
pregnated with  bituminous  matter.    About  ten  miles  to  the  north- 
east of  Baku   are   many  old   temples    of  the  Guebres,  or  fire- 
worshippers,  in  each  of  which  there  is  a  jet  of  inflammable  gas 
issuing  from  apertures  in  the  earth.  Within  an  area  of  two  miles 
in  circumference,  if  holes  be  made  in  the  earth,  gas  immediately 
rises,  and  may  be  set  on  fire  by  a  lighted  torch.    The  inhabitants 

What  is  the  appearance  of  Great  Staple  Tor  ? 

What  character  does  granite  manifest  when  we  attempt  to  divide  it  me- 
chanically  ? 

What  gases  are  evolved  from  volcanos  ? 
Which  two  of  these  are  most  abundant  ? 
What  peculiar  appearance  has  been  observed  west  of  the  Caspian  Sea  ? 

*  Dr.  Boase,  who,  from  analogy  of  structure  between  granitic  and  schis- 
tose rocks,  infers  their  common  origin,  has  adduced  sufficient  evidence  of 
an  approach  to  stratification  in  the  former.  See  his  Treatise  on  Primary 
Geology.  1834.  ch.  vi. 

t  Memoire  surles  Isles  Ponces,  &c.,  pp.  360 — 363. 


EVOLUTION  OF  GASES  FROM  THE  EARTH.       329 

fix  hollow  canes  in  such  holes,  and  light  the  stream  of  gas  from 
the  top,  availing  themselves  of  the  light  and  heat  for  domestic 
purposes.  The  flame  is  easily  extinguished  by  plugging  up  the 
orifice  of  the  tube.  Besides  the  sacred  and  domestic  fires,  there 
is  a  large  one  which  springs  from  a  natural  cliff  in  an  open  situa- 
tion, and  which  burns  continually. 

88.  Mr.  Kinneir  states,  that  the  whole  country  round  Baku  has 
at  times  the  appearance  of  being  enveloped  in  flames.     "  It  often 
seems,"  he  says,  "  as  if  the  fire  rolled  down  from  the  mountains 
in  large  masses,  and  with  incredible  velocity ;  and  during  the 
clear  moonshine  nights  of  November  and  December,  a  bright  blue 
light  is  observed  at  times  to  cover  the  whole  western  range.  This 
fire  does  not  consume,  and  if  a  person  finds  himself  in  the  middle 
of  it  no  warmth  is  felt."* 

89.  Captain  Beaufort  describes  an  ignited  jet  of  inflammable 
gas,  called  the  Yanar,  near  Delictash,  on  the  coast  of  Karamania, 
anciently  perhaps  the  object  of  religious  veneration.     He  states, 
that  "in  the  inner  corner  of  a  ruined  building,  the  wall  is  so  un- 
dermined as  to  leave  an  aperture  of  about  three  feet  in  diameter, 
and  shaped  like  the  mouth  of  an  oven  :  from  this  the  flame  issues, 
giving  out  an  intense  heat,  yet  producing  no  smoke  on  the  wall." 
Though  the  wall  was  scarcely  discoloured,  a  little  caked  soot 
appeared  in  the  neck  of  the  aperture.     The  hill  is  composed  of 
crumbly  serpentine,  and  loose  rocks  of  limestone.     At  a  short 
distance  down  the  hill  there  is  another  aperture,  which,  from  its 
appearance,  may  have  given  out  gas.     The  Yanar  is  supposed  to 
be  of  ancient  date,  Pliny  having  described  a  similar  phenomenon, 
probably  with  reference  to  this  spot.f     Such  jets  of  inflammable 
gas  have  been  observed  in  a  mountain  in  the  island  of  Samos,  in 
a  temple  at  Chittagong  in  Bengal,  and  near  salt  springs  in  China. 

90.  Both  in  Europe  and  America  the  spontaneous  production 
of  carburetted  hydrogen  has  been  taken  advantage  of  for  econo- 
mical purposes.     In  the  salt  mine  of  Gottesgabe,  at  Reine,  in  the 
county  of  Tecklenberg,  there  is  an  opening  called  the  Pit  of  the 
Wind,  from  which  a  continuous  current  of  this  gas  has  issued  for 
sixty  years.     M.  Roeders,  inspector  of  the  mines,  has,  for  a  few 
years  past,  employed  this  natural  gaslight  for  the  purposes  of 
illumination  and  for  cookery.^: 

91.  Near  the  village  of  Fredonia,  New  York,  are  a  number  of 
what  are  called  burning  springs ;  and  gas  issues  from  them,  which 

xTo  what  useful  purpose  is  it  applied  ? 
What  peculiarity  belongs  to  the  Baku  gas  fires? 
What  is  the  situation  and  appearance  of"  the  Yanar  ? 

*  See  Hanway's  Travels  in  Persia,  vol.  i. ;  Geo.  Forster's  Travels  over 
land  to  India;  Macdonald  Kinneir's  Geographical  Memoir  on  Persia; 
Engelhard  t  and  Parrot's  Travels  in  the  Crimea  and  Caucasus  in  1815,  vol. 
'. ;  and  Humboldt  Fragmens  Asiatiques. 

t  Karamania,  or.  Brief  Description  of  the  Coast  of  Asia  Minor.    1817. 

jf  Edinb.  Journal  of  Science,  No.  xv.  p.  183. 
2E2 


330  GEOLOGY. 

is  collected  in  a  gasometer,  and  conveyed  by  pipes  to  the  village, 
which  is  thus  lighted.  The  same  kind  of  gas  is  evolved  more 
copiously  in  the  bed  of  a  stream  about  a  mile  from  the  village.  It 
consists  of  carburetted  hydrogen,  supposed  to  be  derived  from 
beds  of  bituminous  coal.*  A  current  of  gas  resembling  this  last 
was  discovered  in  1828,  in  the  bed  of  a  rivulet  which  crosses  the 
north  road  between  Edinburgh  and  Glasgow,  about  seven  miles 
from  the  latter  city.  It  is  said  to  be  emitted  for  more  than  half 
a  mile  along  the  banks  of  the  rivulet ;  and  in  one  place,  where 
many  jets  issued  within  a  yard  square,  it  was  set  on  fire,  and 
burnt  uninterruptedly  during  five  weeks,  giving  the  clay  soil  the 
appearance  of  powdered  brick. f 

92.  The  extrication  of  inflammable  gases  from  the  bowels  of 
the  earth  is  interesting,  as  tending  to  illustrate  the  peculiar  geo- 
logical structure  of  various  distant  portions  of  the  earth's  surface; 
and  the  gases  issuing  from  volcanic  districts  must  have  some  in- 
fluence on  the  nature  of  the  minerals  occurring  in  such  situations ; 
but  the  quantities  in  which  they  are  thus  produced  are  relatively 
insignificant,  and  their  formative  or  destructive  effects  must  take 
place  to  an  extent  far  inferior  to  those  occasioned  by  oxygen  and 
carbonic  acid. 

93.  Gases  are  not  the  only  kinds  of  foreign  matter  contained 
in  the  atmosphere,  which  forms  a  receptacle  for  all  such  bodies, 
whether  fluid  or  solid,  as  are  at  any  time  exposed  to  its  action, 
and  are  rendered  capable  of  elevation  by  their  inferiority  of  spe- 
cific gravity.     Water,  however,  appears  to  be  the  only  kind  of 
matter  which  occurs  in  sufficient  quantities  in  the  atmosphere,  to 
produce  any  considerable  effect  on  the  surface  of  the  earth  in  con- 
sequence of  its  chemical  properties.     From  its  solvent  power  it 
must  materially  aid  the  operation  of  carbonic  acid  in  the  decom- 
position of  rocks,  and  that  property  alone,  as  it  is  widely  dis- 
persed, and  in  some  places  in  great  abundance  in  the  lower  strata 
of  the  air,  renders  it  a  formidable  agent  of  destruction. 

94.  It  has  sometimes  been  supposed  that  the  atmosphere  ab- 
stracts water  from  the  sea,  holding  in  solution  muriatic  acid  or 
salts.    But  from  the  experiments  of  M.  Roubaudi  at  Nice,  on  the 
coast  of  the  Mediterranean,  it  appears  that  when  the  sea  is  calm, 
the  air  on  the  sea-shore  and  over  the  sea,  contains  neither  muriatic 
acid  nor  muriates,  though  when  the  sea  is  rough,  and  particularly 
if  the  wind  is  high,  particles  of  sea-water,  in  a  state  of  great 
tenuity,  float  in  the  air,  but  the  distance  to  which  they  may  be 

What  use  is  made  of  the  carburetted  hydrogen  from  natural  sources  ? 

What  is  the  probable  influence  of  inflammable  gases,  compared  with 
that  of  oxygen  and  hydrogen  ? 

What  is  the  relative  influence  of  moisture  on  the  texture  of  the  earth's 
surface  ? 

What  is  the  condition  in  regard  to  freshness  or  saltness  of  water  evapo- 
rated from  the  ocean  ? 

*  Edinb.  Journ.  of  Science,  No.  xy.  p.  183. 

t  Edinb.  Journal  of  Science,  No.  i.,  N.  S.  pp.  71 — 75. 


SHOWER  OF  VOLCANIC  DUST.  331 

carried  inland,  will  necessarily  depend  on  the  force  and  direction 
of  the  wind.* 

95.  The  action  of  the  atmosphere  on  the  superficial  strata  of 
the  earth  varies  according  to  the  circumstances  under  which  it 
takes  place.    When  it  is  in  a  state  of  repose  its  effects  must  prin- 
cipally depend  on  its  properties  as  a  chemical  agent ;  and  these 
have  been  already  noticed.     Air,  when  in  a  state  of  agitation,  as 
during  the  prevalence  of  winds,  storms,  tempests,  hurricanes,  and 
tornados,  becomes  a  mechanical  agent  of  vast  power ;  but  its  in- 
fluence is  so  generally  blended  with  that  of  aqueous  showers  and 
currents,  that  it  is  difficult  to  ascertain  the  exact  extent  to  which 
it  operates ;  and  as  the  subject  of  aerial  oscillations  and  disturb- 
ances belongs  to  meteorology,  a  few  observations  only  will  be 
requisite  here  relative  to  the  effect  of  commotions  in  the  atmos- 
phere on  the  surface  of  the  earth. 

96.  Even  when  the  air  is  perfectly  still,  the  power  of  gravita- 
tion necessarily  causes  the  ascent  of  all  loose  bodies  from  the 
earth,  which  are  inferior  in  specific  gravity  to  the  lower  aerial 
strata,  and  extremely  minute  particles  of  heavier  matters  are  also 
elevated,  probably  from  the  action  of  temperature,  producing  mode- 
rately ascending  currents.    It  is  in  consequence  of  their  wonderful 
tenuity,  that  the  seeds  of  cryptogamous  plants,  as  mosses,  fungi, 
and  lichens,  are  often  transported  to  great  distances  through  the 
air,  and  thus  such  plants  are  found  vegetating  in  situations  in 
which  it  would  be  impossible  otherwise  to  account  for  their  exist- 
ence.    "  The  sporules  of  fungi,"  observes  Fries,  "  are  so  infinite, 
that  in  a  single  individual  of  Reticularia  maxima,  I  have  counted 
above  ten  millions,  and  so  subtle  as  to  be  scarcely  visible,  often 
resembling  thin  smoke,  so  light  that  they  may  be  raised,  perhaps, 
by  evaporation  into  the  atmosphere,  and  dispersed  in  so  many 
ways  by  the  attraction  of  the  sun,  by  insects,  wind,  elasticity, 
adhesion,  &c.,  that  it  is  difficult  to  conceive  a  place  from  which 
they  may  be  excluded."! 

97.  To  what  great  distances  heavy  substances  in  a  state  of  minute 
division  may  be  conveyed  through  the  air,  will  appear  from  the 
following  observations,  made  at  Barbados,  during  a  volcanic  erup- 
tion in  the  island  of  St.  Vincent's,  which  is  about  seventy  miles 
directly  westward  from  it:  "In  the  night  preceding  the  1st  of 
May,  1812,  the  inhabitants  of  the  garrison  of  Barbados  were 
alarmed  by  the  noise  of  explosions  from  the  westward,  which 
seemed  to  proceed  from  fleets  engaged  at  sea  in  that  direction.   At 
two  pr  three  in  the  morning  there  was  a  strange  sort  of  dust  drop- 
On  what  two  principles  does  the  modifying  action  of  the  air  depend  ? 
How  is  the  ascent  of  bodies  in  the  air  to  be  accounted  for  ? 

What  evidence  have  we  of  the  transportation  of  vegetable  and  other 
substances  through  the  air  ? 

What  striking  examples  can  be  cited  of  the  transportation  of  heavy 
materials  through  the  air? 

*  Journal  de  Pharmacie.    1833. 

t  Lindley's  Introduction  to  the  Natural  System  of  Botany. 


332  GEOLOGY. 

ping  from  the  air,  which  increased  as  the  morning  advanced. 
When  daylight  appeared,  a  large  body  of  vapour  appeared  to  the 
northward  of  the  east,  slowly  advancing  over  the  island,  pro- 
ducing, in  a  manner  sufficiently  obvious,  a  darkness  in  the  quarter 
from  which  it  came,  carrying  before  it  a  bright  portion  of  the  sky, 
bounded  by  an  apparently  circular  line  of  dimensions  successively 
diminishing  until  entirely  shut  in,  and  complete  darkness  covered 
all  things.  The  ordinary  darkness  of  night,  always  illuminated 
more  or  less  by  starlight,  was  not  to  be  compared  to  this.  It  was 
total  and  absolute.  The  eye  could  not  see  the  hand.  It  was  an 
Egyptian  darkness  that  might  be  felt.  The  dust  continued  to  in- 
crease, and  fell  in  such  large  quantities,  as  to  cover  every  thing 
to  the  depth  of  more  than  an  inch,  and  even  to  break  down  the 
branches  of  trees  by  lying  on  them.  Between  twelve  and  one 
o'clock  in  the  day,  a  vertical  shadowy  light  began  to  appear,  the 
passage  of  light  from  the  atmosphere  above  being  shortest  in  that 
direction  through  the  dust,  in  a  circular  form,  which,  as  the  dust 
thinned  away  or  drove  on,  increased  in  diameter,  until  the  whole 
body  of  particles  passed  away  visibly. 

98.  By  the  impalpable  particles  of  dust  thus  deposited,  for 
many  days  men  and  animals  were  grievously  annoyed ;  even  the 
tender  leaves  of  plants  were  injured,  and  the  wind  agitating  the 
dust,  the  whole  face  of  the  country  showed  like  the  crater  of  a 
volcano.     The  volcano  of  St.  Vincents  had  burst  out.    The  dust, 
thrown  by  explosions  to  considerable  heights,  had,  by  the  higher 
currents  of  air,  been  carried  to  windward  during  the  night,  and, 
descending  into  the  lower  regions  of  the  atmosphere,  was  driven 
back  over  the  island  by  the  ordinary  tradewind  a  little  to  the  north 
of  east.     During  the  fall,  patterings  on  the  roofs  of  houses,  as  of 
grosser  particles  than  dust,  were  repeatedly  heard,  and  some  of  the 
dust  sent  to  me  contained  particles  of  stones,  whose  dimensions 
seemed  to  exceed  all  the  power  of  floatage,  so  gross,  that  I  was 
led  to  conceive  that  they  were  carelessly  taken  up  from  the  soil  on 
which  the  dust  lay.     Other  portions  of  the  dust  were  free  from 
these.     An  analysis  of  this  dust,  in  the  laboratory  of  the  Royal 
institution,  by  Mr.  Faraday,  gives  the   following  components : 
silex  78,  alumine  11.2,  lime  7,  oxide  of  iron  .3.4,  loss  .4  =  100.* 

99.  "  This  floatage  power  of  small  bodies  may  account  for  the 
dust  said  to  be  observed  on  the  tops  of  the  highest  mountains,  to 
which  the  finest  particles  of  smoke,  and  of  whatever  solid  materials 
may  be  adequately  divided,  so  as  to  be  elevated  and  dispersed  in 

Desenhe  the  phenomena  accompanying  the  eruption  at  St.  Vincents? 
How  is  the  particular  current  of  the  shower  of  dust  in  that  case  to  be  ac- 
counted for  ? 

What  effect  did  it  produce  on  the  roofs  of  buildings? 

What  was  found  to  be  the  composition  of  the  material  then  collected  ? 

How  is  the  dust  on  the  surface  of  high  mountains  to  be  accounted  for? 

*  The  small  amount  of  loss,  about  l-200th  of  the  whole,  may  probably 
have  been  owing  to  the  -escape  of  hygroraetric  moisture- 


INUNDATIONS  OF  SAND.  333 

air,  may  rise,  and  in  a  given  state  of  rest  in  the  air  above,  unknown 
below,  may  quietly  be  deposited,  and  undisturbedly  repose."* 

100.  During  an  eruption  from  the  volcanic  mountain  of  Tomboro, 
in  the  island  of  Sumbawa,  in  1815,  which  will  be  subsequently 
noticed,  the  fall  of  dust  and  ashes  was  so  great  at  Bima,  forty 
miles  eastward  of  the  volcano,  as  to  break  down  the  roofs  of  the 
residency  and  other  houses ;  and  on  the  side  of  Java,  the  volcanic 
powder  was  carried  300  miles,  and  more  than  200  towards  Celebes, 
in  sufficient  quantity  to  darken  the  air. 

101.  The  influence  of  the  atmosphere  in  modifying  the  surface 
of  the  earth  must  obviously  be  greatly  augmented   during  the 
prevalence  of  high  winds.    Thus  are  formed  dunes  and  sand-hills, 
which  sometimes  overwhelm  cultivated  fields,  and  the  habitations 
of  man,  transforming  fertile  plains  into  barren  trackless  wastes. 
Such  phenomena  have   taken  place  in  the  south  of  France,  in 
Egypt,  and  in  different  parts  of  Scotland. 

102.  Cuvier  remarks,  that  where  the  sand  thrown  up  by  the  sea 
is  left  loose,  it  advances  as  irresistibly  over  the  land  as  the  silt 
and  other  alluvial  matter  carried  down  by  rivers  does  over  the  bed 
of  the  sea.     In  their  progress  the  sands  push  before  them  large 
pools  formed  by  rain,  intercepting  their  communication  with  the 
sea.     On  the  coast  of  the  Bay  of  Biscay  they  have  overwhelmed 
many  villages  mentioned  in  records  of  the  middle  ages  ;  and  in  the 
department  of  the   Landes  alone,  ten  are   now  threatened"  with 
destruction.    Mimisan,  one  of  these  villages,  has  for  twenty  years 
been  struggling  against  them,  while  a  sand-hill  more  than  sixty 
feet  in  height  is  approaching  it.  Their  progress  has  been  estimated 
at  sixty  feet  annually,  and  in  some  places  at  seventy-two  feet. 
According  to  this  calculation  they  might  in  two  thousand  years 
reach  Bourdeaux ;  and,  from  their  present  extent,  it  must  have 
been  about  four  thousand  years  since  they  began  to  be  formed.| 

103.  The  sands  of  the  Libyan  deserts,  driven  by  the  west  winds, 
have  covered  all  the  land  formerly  capable  of  tillage  on  the  western 
bank  of  the  Nile.     Denon,  in  his  "  Travels  in  Lower  and  Upper 
Egypt,"  says  that  the  summits  of  the  ruins  of  ancient  cities  buried 
under  these  sands  still  appear  externally. 

104.  In  Morayshire,  N.  B.,  westward  from  the  mouth  of  the 
river  Findhorn,  a  district  consisting  of  more  than  ten  square  miles 
of  land,  once  termed,  from  its  fertility,  the  Granary  of  Moray,  has 
been  depopulated  and  ruined  by  a  sand-flood.     The  eruption  com- 
menced about  1677,  and  its  progress  was  gradual ;  but  in  1697  not 

What  evidence  of  extensive  motion  in  masses  of  dust  is  found  in  the 
East  Indies? 

On  what  causes  ie  the  formation  of  sand-hills  supposed  to  depend  ? 
What  operation  ie  effected  by  the  wind  on  sands  upon  the  sea-coast? 
What  examples  of  this  are  found  in  Europe? — in  Egypt? 

*  On  the  Floatage  of  Small  Heavy  Bodies  in  Air,  by  G.  W.  Jordan,  F 
R  S.,  Journ.  of  Science,  vol.  viii,  pp,  251 — 253. 
^  Cuvier's  Theory  of  the  Earth,  pp,  133—135, 


334  GEOLOGY. 

a  vestige  was  to  be  seen  of  the  manor-house,  orchards,  and  offices 
of  Coubine,  two-thirds  of  the  barony  so  called  having  been 
destroyed,  and  the  sand  was  daily  gaining  ground.  This  sand 
came  from  Mavieston,  on  the  coast,  seven  miles  west  from  the 
mouth  of  the  Findhorn,  where  from  time  immemorial  there  have 
been  large  accumulations  of  sand.  It  appears,  however,  that  the 
catastrophe  of  Coubine  "was  occasioned  by  the  bad  practice  of 
pulling  bent  and  juniper,"  which  occasioned  an  act  of  the  Scottish 
Parliament,  dated  July  16,  1695,  for  the  preservation  of  lands  ad- 
jacent to  sand-hills.  The  cause  thus  assigned  as  the  origin  of  the 
devastation  of  Coubine,  suggests  an  obvious  remedy,  in  the  plan- 
tation of  vegetables  which  will  grow  in  a  sandy  soil,  such  as  the 
Jlrundo  arenaria,  and  the  Elymus  arcnar'ius,  the  spreading  fibrous 
roots  of  which  give  stability  to  the  loose  surface.* 

105.  Sands  and  fragments  of  sea-shells  are  sometimes  raised 
from  the  beach  to  very  considerable  heights  by  violent  winds,  as 
is   the   case  with  the  sands  of  Barry,  at   the  north  side  of  the 
estuary  of  the  Tay,  Scotland,  where  hills  have  been  formed  by 
them  140  feet  high.f 

106.  Hurricanes,  from  their  extraordinary  force  and  violence 
productive  of  effects  far  beyond  those  of  high  winds,  are  generally 
accompanied  by  storms  of  rain,  and  the  result  of  their  influence, 
therefore,  is  partly  owing  to  the  impulse  of  gusts  of  air,  and  partly 
to  that  of  floods  of  water.     "They  are  of  geological  importance," 
says  Mr.  De  la  Beche,  "  as  by  the  sudden  application,  if  I  may  so 
express  myself,  of  a  furious  wind  and  deluges  of  rain  to  the  surface 
of  land,  very  considerable  changes  are  in  a  short  time  produced  on 
that  surface. "+     The  velocity  of  the  wind  in  hurricanes  has  been 
estimated  at  from  eighty  to  one  hundred  miles  an  hour. 

107.  The  hurricanes  that  occasionally  ravage  the  Antilles,  the 
Isles  of  France  and  Bourbon,  Siam,   China,  Japan,  and   other 
countries  between  and  near  the  tropics,  overthrow  solid  edifices, 
uproot  the  strongest  trees,  involve  animals  and  the  produce  of  the 
fields  in  one  common  ruin,  and  sweep  to  a  distance  vast  masses  of 
solid  matter.  The  desolating  power  of  hurricanes  may  be  estimated 
from  the  ensuing  account  of  one  which  visited  Guadeloupe,  July  25, 
1825.  Houses  firmly  built  were  overturned  ;  and  a  new  structure, 
erected  at  the  expense  of  the  government,  in  a  most  substantial 
manner,  was  ruined.     The  force  and  rapidity  of  the  wind  was 
such  as  to  drive  tiles  through  the  thick  doors  of  warehouses.     A 
deal  plank,  about  39  inches  long,  9^.  inches  wide,  and  T9^  of  an 
inch  thick,  was  carried  with  such  extraordinary  velocity  through  the 

How  is  the  motion  of  sand-hills  to  be  prevented  ? 

Of  what  importance  are  hurricanes  in  a  geological  point  of  view  ?  How 
is  this  proved  ? 
Describe  the  effects  observed  in  the  tornado  of  Guadaloupe? 

*  See  Illustrations  of  Cuvier's  Theory  of  the  Earth,  by  Prof.  Jameson. 
Note  G. 

t  I/yell's  Princip.  of  Geol.,  vol,  i.  p.  313. 
J  Geolog.  Man.,  p.  149. 


DESTRUCTION  OF  ROCKS  BY  MOISTURE.  335 

air,  that  it  passed  directly  through  the  trunk  of  a  palm-tree  17T7T 
inches  in  diameter.  A  piece  of  wood  7.J  inches  square,  and  from 
4  to  5  yards  in  length,  was  driven  by  the  wind  through  the  sur- 
face of  a  hard,  beaten,  and  frequented  road,  to  the  depth  of  about 
a  yard.  A  fine  iron  railing  before  the  government  house  was 
entirely  broken.  Three  pieces  of  cannon,  twenty-four  pounders, 
were  dismounted,  and  driven  against  the  breastwork  of  the  battery 
in  which  they  were  placed.  The  accuracy  of  this  statement  was 
verified  by  inquisition  on  the  spot,  by  General  Baudrand,  of  the 
French  engineers.* 

108.  The  effect  of  air  in  modifying  the  surface  of  the  earth, 
where  it  acts  independently,  is  chiefly  the  result  of  its  chemical 
properties :  water  is  perhaps  the  most  efficient  as  a  mechanical 
agent.     The  influence  of  water,  like  that  of  air,  is  apparent  both 
as  a  destructive  and  as  a  formative  or  constructive  power ;  dis- 
solving or  wearing  away  solid    surfaces  in  one   situation,  and 
depositing  beds  of  transported  matter  in  another.     Indeed  these 
operations  must  almost  always  be  simultaneous  or  successive, 
the  detritus  of  rocks  and  of  organic  bodies,  removed  by  the  agency 
of  water  from  the  higher  parts  of  a  country,  serving  to  form  new 
tracts  of  land,  by  filling  up  lakes,  or  composing  deltas,  sandbanks, 
or  islands  encroaching  on  the  sea. 

109.  Mr.  De  la  Beche,  after  describing  the  manner  in  which  the 
disintegration  of  rocks  may  take  place,  owing  to  the  protracted 
action  of  atmospheric  moisture,  and  the  more  rapid  and  violent 
operation  of  streams  and  torrents  in  the  degradation  of  land,  says, 
"  This  destruction  of  the  surface  is  common  to  most  countries ; 
and  if  a  rock  so  weathered  be  limestone,  there  is  not  unfrequently 
a  reconsolidation  of  the  parts  by  means   of  calcareous   matter 
deposited  by  the  water  that  percolates  through  the  fragments,  and 
which  dissolves  a  portion  of  them.  At  Nice,  the  fractured  surface 

In  •what  manner  does  air  produce  the  changes  on  the  earth's  surface  ? 
How  are  the  destructive  processes  of  air  and  of  water  sometimes  coun- 
terbalanced ? 

*  Pouillet  Elem.  de  Phys.  Exper.  et  de  Meteorol.,  torn.  ii.  pp.  717,718. 

A  most  destructive  tornado  passed  over  the  city  of  New  Brunswick, 
on  the  19th  of  June,  1835.  It  was  preceded  by  a  sultry  day,  with  a  very 
high  dew  point,  and  was  attended  with  some  lightning ;  but  the  thunder, 
if  any,  was  drowned  in  the  roar  of  the  tornado.  Rafters,  20  feet  long  and 
8  or  9  inches  wide  by  3  inches  thick,  were  carried  half  a  mile  ;  a  lad,  nine 
years  old,  was  carried  one  quarter  of  a  mile  through  the  air;  more  than 
100  buildings  were  either  demolished,  unroofed,  or  otherwise  injured.  The 
track  was  but  a  few  hundred  yards  in  breadth ;  and  the  editor  of  this 
work,  with  other  gentlemen,  who  visited  the  spot  on  the  day  following, 
observed  that  trees,  grass,  buildings,  &c.  on  the  margin  of  the  track,  had 
been  uniformly  inclined  inward  toward  the  central  line  of  the  path  ;  a 
barn  on  one  margin  and  a  large  store-house  on  the  other,  were  raised  each 
from  its  foundation  and  transported  bodily  some  feet  towards  that  line.  In 
the  forest  the  trees  fell  inward  at  the  margin,  and.  gradually  inclined 
more  and  more  towards  the  point  to  which  the  storm  was  moving,  as  they 
were  nearer  the  centre. — Ed. 


336  GEOLOGY. 

thus  reunited  is  so  hard,  that  if  it  occur  on  a  line  of  road  it  must 
be  blasted  by  gunpowder  for  removal.  There  are  some  fine  ex- 
amples of  this  reconsilidation  upon  the  limestone  hills  of  Jamaica  ; 
as,  for  example,  near  Rock  Fort,  and  at  the  cliffs  to  the  eastward 
of  the  Milk  River's  mouth. 

110.  "The  feldspar  contained  in  granite  is  often  easily  decom- 
posed, and  when  this  is  effected,  the  surface  frequently  presents  a 
quartzose  gravel.     D'Aubuisson  mentions,  that  in  a  hollow  way, 
which  had  been  only  six  years  blasted  through  granite,  the  rock 
was  entirely  decomposed  to  the  depth  of  three  inches.     He  also 
states,  that  the  granite   country  of  Auvergne,  the  Vivarais,  and 
the  eastern  Pyrenees,  is  frequently  so  much  decomposed,  that  the 
traveller  may  imagine  himself  on  large  tracts  of  gravel.* 

"  Some  trap-rocks,  from  the  presence  of  the  same  mineral,  are  so 
liable  to  decomposition,  that  there  is  frequently  much  difficulty  in 
obtaining  a  specimen.  The  depth  to  which  some  rocks  of  this 
nature  are  disintegrated  in  Jamaica  is  often  very  considerable."! 

111.  The  powerful  effect  of  the  continued  action  of  running 
water  on  compact  rock  appears  from  the  manner  in  which  the  river 
Simeto,  in  Sicily,  has  cut  through  a  bed  of  lava.     At  the  western 
base  of  Etna  a  great  current  of  lava  descending  from  near  the  sum- 
mit of  the  principal  volcano,  flowed  over  the  alluvial  plains  of 
Simeto,  the  largest  of  the  Sicilian  rivers,  which  skirts  the  base  of 
the  mountain,  and  falls  into  the  sea  a  few  miles  south  of  Catania. 
The  lava  entered  the  river  about  three  miles  above  the  town  of 
Aderno,  and  not  only  filled  its  channel  for  some  distance,  but 
flowing  to  the  opposite  side  of  the  valley,  accumulated  there  in  a 
rocky  mass.     The  eruption  is  supposed  to  have  taken  place  in 
1603,  and  the  appearance  of  the  current  proves  that  it  is  of  modern 
date,  for  it  has  not  been  crossed  or  covered  by  any  other  stream 
of  volcanic  matter.     In  the  course,  therefore,  of  about  two  cen- 
turies, the  Simeto  has  eroded  a  passage  from  fifty  to  several  hun- 
dred feet  wide,  and  in  some  parts  from  forty  to  fifty  feet  deep. 
The  mass  of  lava  cut  through  is  not  porous  or  scoriaceous,  but  a 
compact,  homogeneous,  hard  blue  rock  ;   and  the  general  declivity 
of  the  bed  of  the  river  in  this  place  is  not  very  considerable.^: 

112.  A  more  striking  example  of  the  detrition  of  solid  rocks  by 
flowing  water  is  exhibited  at  the  falls  of  Niagara.     At  these  falls 
"  the  water  is  divided  by  a  small-island,  which  separates  the  river 
into  two  cataracts,  one  of  which  is  six  hundred  yards,  and  the 
other  three  hundred  and  fifty  yards  wide :  the  height  of  the  fall  is 

What  remarkable  instances  of  the  effect  of  exposing  rock  surface  to  the 
air  have  been  observed  ? 

What  striking  instances  can  be  cited  in  which  the  erosive  action  of  watejr 
has  taken  place  ? 

*  Traite  de  Geognosie ;  ou,  Expose  des  Connaissances  actuelles  sur  la 
Constitution  Physique  et  Minerale  du  Globe  Terrestre,  torn.  i. 
t  Geolog.  Man.  p.  45. 
J  Lyell's  Principle*  of  Geology,  vol.  i.  pp.  258—260. 


EFFECTS  OF  LAND  FLOODS.  337 

from  one  hundred  and  forty  to  one  hundred  and  sixty  feet.  It 
is  estimated  that  670,000  tons  of  water  are  dashed  every  minute 
with  inconceivable  force  against  the  bottom,  and  wearing  down 
the  adjacent  rocks.  Since  the  banks  of  the  cataract  were  inhabited 
by  Europeans,  they  have  observed  that  it  is  progressively  shorten- 
ing the  distance  of  the  falls  from  Lake  Erie.  When  it  has  worn 
down  the  intervening  calcareous  rocks,  the  upper  lake  will  become 
dry  land,  and  form  an  extensive  plain  or  valley,  surrounded  by 
rising  ground,  and  watered  by  a  river  or  smaller  lake,  which  will 
occupy  the  lowest  part.  In  this  plain  future  geologists  may  trace 
successive  strata  of  fresh-water  formation,  covering  the  subjacent 
ancient  limestone.  The  gradual  deposition  of  minute  earthy 
particles,  or  the  more  rapid  subsidence  of  mud  from  sudden 
inundations,  will  form  distinct  beds,  in  which  will  be  found  the 
remains  of  fresh-water  fish,  vegetables,  and  quadrupeds." 

113.  "  Prof.  Joseph  Henry,  in  a  topographical  sketch  of  the  state 
of  New  York,*  says,  *  The  descent  of  the  country  from  Lake  Erie 
to  Ontario,  is  principally  by  a  step,  not  at  the  falls,  but  at  Lewis 
Town,  several  miles  below.     In  viewing  the  position  of  the  falls, 
and  the  features  of  the  country  round,  it  is  impossible  not  to  be 
impressed  with  the  idea,  that  this  great  natural  race-way  has  been 
formed  by  the  continued  action  of  the  irresistible  current  of  the 
Niagara,  and  that   the  falls,   beginning  at  Lewis  Town,  have, 
in  the  course  of  ages,  worn  lack  the  rocky  strata  to  their  present 
site.     The  deep  chasm  through  which  the  Niagara  passes,  be- 
low the  falls,  is  nearly  a  rnile  wide,  with  almost  perfect  mutual 
sides. 

114.  The  bed  of  the  river  below  the  falls  is  strewed  with  huge 
fragments  of  rocks,  hurled  down  by  the  cataract.     The  retrogres- 
sion of  the  waterfall,  owing  to  the  destruction  of  the  surface  over 
which  it  takes  its  course,  is  said  to  have  amounted  to  nearly  fifty 
yards  during  the  last  forty  years.     If  the  excavation  always  pro- 
ceeded at  the  same  rate,  it  must  have  required  about  ten  thousand 
years  for  the  formation  of  the  whole  ravine  f  and  it  would  take  up 
more  than  thirty  thousand  years  from  the  present  time  before  the 
channel  would  be  worn  backward  to  Lake  Erie,  a  distance  of 
twenty-five  miles. 

115.  The  power  of  running  water  in  removing  stones  and  heavy 
materials,  and  changing  the  face  of  a  country,  was  remarkably 
exemplified  in  the  effects  of  the  great  flood  which  happened  in 
August,  1829,  in  the  province  of  Moray,  and  adjoining  districts,  in 
Scotland.     The  storm  which  occurred  on  this  occasion  displayed 
all  the  characteristic  violence  of  a  tropical  hurricane.     The  inun- 

What  change  is  now  taking  place  on  the»rock  at  Niagara  Falls 

What  is  the  nature  of  the  channel  of  the  Niagara? 

At  what  point  did  the  fall  first  exist  ? 

What  known  changes  have  taken  place  in  the  position  of  those  Falls? 

*  Transactions  of  the  Albany  Institute,  vol.  i. 
2F 


338  GEOLOGY. 

dating  rivers  were  the  Nairne,  the  Findhorn,  and  the  Spey,  with 
their  numerous  tributaries.  All  the  low  intervening-  lands  were 
covered,  and  the  bridges  and  buildings  along  the  banks  were  in 
general  swept  away.  The  plain  of  Torres  was  inundated  to  an 
extent  of  twenty  square  miles,  and  the  destruction  every  where 
great.  On  the  Nairne  a  fragment  of  sandstone  rock,  fourteen  feet 
long,  three  feet  wide,  and  one  thick,  was  carried  more  than  two  hun- 
dred yards  down  the  river.  Some  new  ravines  were  scooped  out  on 
tho  sides  of  the  mountains,  where  no  streams  had  previously 
flowed,  and  ancient  river  channels,  which  had  never  been  filled 
from  time  immemorial,  gave  passage  to  copious  floods. 

116.  Sir  Thomas  Dick  Lander,  who  published  a  narrative  of  this 
occurrence,  has  given  the  following  animated  description  of  the 
devastation  which   took  place  in  his  own  ornamented  domain : 
"  We  were  roused  while  at  dinner  by  the  account  the  servants 
gave  us  of  the  swollen  state  of  the  rivers ;  and  in  defiance  of  the 
weather,  the  whole  party  sallied  forth.  We  took  our  way  through 
the  garden,  towards  the  favourite  Mill  Island.     The  magnificent 
trees  on  that  island  were  overthrown  faster  and  faster,  offering  no 
more  resistance  to  their  triumphant  enemy  than  reeds  before  the 
mower's  scythe.     Each  one  as  it  fell  gave  one  enormous  splash 
on  the  surface,  then  a  plunge ;  the  root  appeared  above  water  for 
a  moment;  and  then  uprose  the  stem,  disbranched  and  peeled; 
after  which,  they  either  rolled  round  in  the  caldron,  or  darted  like 
arrows  down  the.  stream.     Besides  the  loss  of  the  Mill  Island, 
which  I  had  looked  for,  the  beautiful  hanging  bank,  covered  with 
majestic  forest  and  ornamental  trees  of  all  kinds,  and  of  growth  so 
fresh  and  vigorous,  had  vanished  like  the  scenery  of  a  dream  ;  and 
in  its  place  was  the  garden  hedge,  running  for  between  two  and 
three  hundred  yards  along  the  brink  of  a  red  alluvial  perpendicular 
precipice,  fifty  feet  high,  with  the  broad,  remorseless  flood  rolling 
at  its  base,  eating  into  its  foundation,  and  every  successive  minute 
bringing  down  masses  of  many  cubic  yards.  And  then,  from  time 
to  time,  some  tall  and*  graceful  tree,  on  the  brink  of  the  fractured 
portions  of  the  bank  at  either  end,  would  slowly  and  magnificently 
bend  its  head,  and  launch  into  the  foaming  waves  below.     The 
whole  scene  had  an  air  of  unreality  about  it  that  bewildered  the 
senses.     It  was  like  some  of  those  wild  melodramatic  exhibitions, 
where  nature's  operations  are  out-heroded  by  the  mechanist  of  a 
theatre,   and   where  mountains   are  thrown   down   by  artificial 
storms."* 

117.  A  bridge  of  granite  over  the  Dee,  at  Ballatu,  consisting  of 
five  arches,  with  a  water-way  of  260  feet,  which  had  stood  firm 
for  twenty  years,  was  destroyed  and  swept  away  by  the  torrent, 

4p 

What  remarkable  effect  of  floods  has  been  witnessed  in  Scotland  ? 
What  account  has  Lauder  given  of  that  occurrence  ? 

*  An  Account  of  the  Great  Floods  of  August,  1829,  in  the  Province  of 
Moray,  by  Sir  T.  D.  Lauder,  Bart.,  1830. 


CHANGES  EFFECTED  BY  RUNNING  WATER.  339 

the  whole  mass  of  the  masonry  having1  disappeared  in  the  bed  of 
the  river.  "  The  river  D6n,"  says  Mr.  Farquharson,  in  his  account 
of  this  catastrophe,  "  has,  upon  my  own  premises,  forced  a  mass 
of  four  or  five  hundred  tons  of  stones,  many  of  them  two  or  three 
hundred  pounds  weight,  up  an  inclined  plane,  rising-  six  feet  in 
eight  or  ten  yards,  and  left  them  in  a  rectangular  heap,  about  three 
feet  deep,  on  a  flat  ground;  the  heap  ends  abruptly  at  its  lower 
extremity."* 

118.  Animals,  as  well  as  trees  and  the  produce  of  the  fields, 
were  involved  in  the  general  ruin  caused  by  the  flood,  the  effects 
of  which  at  the  mouth  of  the  river  Spey  are  thus  described  :   "  For 
several  miles  along  the  beach,  crowds  were  employed  in  endea- 
vouring to  save  the  wood  and  other  wreck  with  which  the  heavy 
rolling  tide  was  loaded  ;  whilst  the  margin  of  the  sea  was  strewed 
with  the  carcasses  of  domestic  animals,  and  with  millions  of  dead 
hares  and  rabbits.  Thousands  of  living  frogs  also,  swept  from  the 
fields,  no  one  can  say  how  far  off,  were  observed  leaping  among  the 
wreck."f 

119.  It  has  been  remarked,  that  the  transporting  effect  of  water 
is  vastly  augmented  by  the  relative  diminution  of  specific  gravity 
in  bodies  more  or  less  immersed  in  that  fluid  ;:J:  and  when  ice 
adheres  to  detached  rocks,  the  joint  masses  become  really  lighter 
than  the  stony  substances  would  be  separately.     Hence  we  may 
in  some  measure  account  for  the  distribution  of  large  blocks  of 

franite   over   the   surface  of  several  parts  of  Europe,  at  great 
istances  from,  the  primitive  rocks  whence  they  appear  to  have 
been  derived. 

120.  The  phenomena  caused  by  floods,  debacles,  and  torrents, 
manifesting  the  sudden  effect  of  powerful  impetus,  imposing  as 
they  are,  cannot  have  contributed  so  extensively  to  the  production 
of  the  changes  apparent  on  the  surface  of  the  earth,  as  the  slow 
but  indefinitely  protracted  operation  of  running  water  more  or  less 
loaded  with  silt  and  sand,  and  conveying  it  from  higher  to  lower 
levels,  to  extend  the  limits  of  old  continents,  or  form  the  founda- 
tions of  new  ones.  Professor  Robinson,  in  an  article  on  "  Rivers," 
in  the  Encyclopaedia  Britannica,  has  furnished  some  estimates  of 
the  effects  of  flowing  water,  whence  it  appears  that  a  velocity  of 
three  inches  per  second  at  the  bottom  will  just  begin  to  act  upon 
fine  clay  in  a  firm  state,  and  tear  it  up  :  a  velocity  of  six  inches 

What  evidence  is  afforded,  by  the  flood  of  1829,  that  rocks  and  boulders 
may  ^n  other  parts  of  the  earih'have  been  dislodged  and  worn  by  water  ? 

What  effect  had  that  flood  upon  animals  ? 

In  what  manner  may  blocks  of  granite  have  been  transported  from  place 
to  place  on  or  near  the  surface  of  water  ? 

By  what  means,  besides  by  floods  and  torrents,  does  water  operate  to 
change  the  surface  of  the  earth  ? 

*  Account  of  the  Flood,  by  the  Rev.  James  Farquharson,  in  Quarterly 
Journal  of  Science,  New  Series,  No.  xii.  p.  331. 
t  Sir  T.  D.  Lauder's  Account,  p.  312. 
t  See  Scientific  Class  Book,  part  i.  pp.  130  and  160. 


340  GEOLOGY, 

will  lift  fine  sand,  that  of  eight  inches  will  raise  sand  as  coarse  as 
linseed,  twelve  inches  will  sweep  away  fine  gravel,  twenty-four 
inches  will  roll  along  rounded  pebbles  an  inch  in  diameter;  and 
it  requires  a  velocity  of  three  feet  per  second  to  sweep  along 
shivery  angular  stones  of  the  size  of  an  egg. 

121.  Whatever  matters  may  be  taken  up  by  flowing  water  will 
be  again  deposited  as  soon  as  the  velocity  of  the  stream  becomes 
inferior  to  that  which  caused  their  removal ;  so  that  only  the  finer 
particles  of  detritus  will  in  general  be  carried  into  the  sea.     The 
distance  to  which  river-water,  loaded  with  such  particles,  would 
flow  over  sea-water,  must  deppnd  on  a  variety  of  obvious  circum- 
stances.   Captain  Sabine  found  discoloured  water,  supposed  to  be 
that  of  the  Amazons,  300  miles  distant  in  the  ocean  from  the  em- 
bouchure of  that  river.     It  was  about  126  feet  deep.     Its  specific 
gravity  was  =  1.020J,  and  the  specific  gravity  of  the  sea-water  = 
1.02G2.     This  appears  to  be  the  greatest  distance  from  land  at 
which  river-water  has  been  detected  on  the  surface  of  the  ocean.* 

122.  The  quantity  of  detrital  matter  conveyed  by  the  rivers  to 
the  sea  must  be  greatly  influenced  by  the  nature  of  the  countries 
through  which  they  take  their  course.   The  Hoang-ho,  or  \  ellow 
river  of  China,  flows  through  alluvial  tracts,  and  the  quantities 
of  mud  and  earth  carried  down  by  its  current  gives  the  water  the 
appearance  of  diluted  clay.    According  to  Mr.  Barrow,  it  pours 
into  the  sea  every  hour  2000  feet  of  solid  earth,  sufficient  in  seventy 
days,   if  accumulated   on   one   spot,   to   form  an  island  a  mile 
in  circumference ;  and  it  has  been  observed,  that  a  sensible  di- 
minution takes  place  in  the  depth  of  the  Yellow  sea,  into  which 
the  turbid  river  discharges  itself.   The  addition  of  lands  that  have 
been  made  in  the  Netherlands,  along  the  shores  of  the  North  sea; 
in  Italy,  on  the  borders  of  the  Adriatic;!  and  in  Egypt,  at  the 
mouth  of  the  Nile  ;  together  with  many  other  phenomena  of  a 
similar  nature  have  been  noticed  by  historians  and  geologists.^: 

123.  The  alluvial  matter  conveyed  to  the  sea  by  great  rivers 
may  not  only  produce  deltas  or  additions  of  land  to  the  coast,  but 
also  give  rise  to  insular  formations.     This  has  taken  place  at  the 
mouth  of  the  Ganges,  which  during  the  flood  season  pours  into 
the  gulf  such  a  quantity  of  mud  and  sand,  that  the  sea  only  recovers 
its  transparency  at  the  distance  of  sixty  miles  from  the  shore. 
Hence  an  island  has  arisen  opposite  the  mouth  of  the  Hoogly 

Mention  the  velocities  which  have  been  found  adequate  to  wear  away 
the  bottoms  of  rivers  of  different  materials? 

How  does  it  appear  that  the  features  of  a  country  may  be  changed  by 
alluvial  deposits  ? 

*  De  la  Beche's  Geol.  Researches,  p.  72, 

t  According  to  Strabo,  Ravenna,  in  the  time  of  Augustus,  stood  among 
lagunes,  as  Venice  does  now,  and  at  present  the  former  city  is  a  league 
distant  from  the  shore. 

t  See  Cuvier's  Theory  of  the  Earth,  pp.  123—132.  Also  Transactions 
of  the  British  Association  at  Ediaburg,  in  1834. 


FORMATION  OF  VALLIES.  341 

river,  (one  of  the  branches  of  the  Ganges,)  and  immediately  south 
of  Saugur  island,  four  miles  from  the  nearest  land  of  the  delta. 
It  is  said  to  have  been  discovered  in  1816,  together  with  the  canal 
dividing-  it  from  Saugur.  It  is  situated  21°  35'  N.  latitude,  and 
88°  20'  E.  longitude,  from  Greenwich ;  its  position  agreeing  with 
that  assigned  to  the  bank  of  Saugur.  A  lighthouse  has  been 
erected  on  this  spot,  which  is  named  Edmonston  island.  For 
many  years  it  has  been  covered  with  shrubs  and  herbage ;  but  the 
whole  surface  was  inundated  for  some  hours  during  the  flood  in 
May,  1833,  the  light-keepers  having  escaped  destruction  by  as- 
cending into  the  lantern.  Its  dimensions  before  that  time  were 
stated  to  be  two  miles  from  east  to  west,  and  half  a  mile  from 
north  to  south ;  but  it  was  reduced  in  size  by  the  inundation,  and 
must  have  since  been  enlarged."* 

124.  Dr.  Hutton  ascribed  the  formation  of  valleys  on  the  surface 
of  the  earth  to  the  erosive  action  of  rivers,  as  a  general  cause  ;f 
and    though  the  more  extensive  observations  of  subsequent  in- 
quirers render  his  conclusions  questionable,  there  can  be  no  doubt 
but  in  some  situations  valleys  may  be  thus  produced.     The  ef- 
fect of  flowing  water  must  depend  on  its  rapidity  and  consequent 
impetus  ;  and  hence  compact  rocks  occasionally  have  their  surfaces 
ploughed  with  gullies  and  hollows  by  the  power  of  mountain 
streams     Dr.  Bigelow,  in  describing  the  White  mountains  of  New 
Hampshire,  says:  "  In  several  places  a  broad  continued  stripe  de- 
scended the  mountains,  having  the  appearance  of  a  regular  road  cut 
through  the  trees  and  rocks  from  near  the  base  to  the  summit.    On 
examining  these  with  a  telescope,  they  were  found  to  be  channels 
of  streams,  and  in  several  places  the  water  could  be  seen  dashing 
down  the  rocks. 

125.  "  In  a  plain  near  the  base  of  the  mountains  was  a  pond  of 
one  or  two  acres,  situated  near  the  road,  and  which  having  no 
other  inlet  or  outlet,  appeared  to  be  the  principal  source  of  the 
Saco  river.     The  waters  of  this  stream,  being  collected  from 
several  sources,  proceed  directly  towards  the  side  of  the  moun- 
tain.    At  the  point  where,  to  all  appearance,  they  must  be  inter- 
cepted in  their  course,  there  occurs  one  of  the  most  extraordinary 
features  of  the  place,  well  known  by  the  name  of  *  the  Notch.' 
The  whole  mountain,  which  otherwise  forms  a  continued  range, 
is  here  cloven  quite  down  to  its  base,  affording  a  free  opening  to 
the  waters  of  the  Saco,  which  pass  off  with  a  gradual  descent 
towards  the  sea.     This  gap  is  so  narrow   that  space  has  with 
difficulty  been  obtained  for  the  road,  which  follows  the  course  of 
the  Saco  through  the  Notch  to  the  eastward.     In  one  place  the 

How  is  this  illustrated  in  China? — in  Hindostan? 

To  what  did  Hutton  attribute  the  formation  of  valleys? 

In  what  manner  is  the  effect  of  water  produced  in  mountain  torrents? 

Describe  the  effect  of  torrents  on  the  White  mountains  ? 

*  Monthly  Magazine— Lyell's  Prin.  of  Geol.  vol.  i.  p.  354. 
t  See  De  Luc's  Elementary  Treatise  on  Geology,  translated  from  the 
French,  by  the  Rev.  H.  De  la  Fite.  1809.  p.  89. 
2  F  2 


342  GEOLOGY. 

river  disappears,  being  lost  in  the  caves  and  crevices  of  the  rocks, 
and  under  the  shelves  of  the  adjoining  precipice,  reappearing  at 
length  at  the  distance  of  some  rods  below.  The  Notch  gradually 
widens  into  a  long  narrow  valley."*  It  appears  that  the  upper 
part  of  the  rock  was  gneiss  and  granite ;  and  near  the  Notch, 
chiefly  course  reddish  jasper,  and  phorphyry.f 

126.  The  manifest  effect  of  lakes  must,  in  general,  be  formative, 
rather  than  destructive,  contributing  to  the    production  of  new 
strata,  by  moderating  the  influence  of  running  water,  and  furnish- 
ing cavities  for  the  deposit  of  detrital  matter.     But  the  bursting 
of  the  banks  by  which  lakes  are  restrained  may  occasion  inun- 
dations and  debacles,  causing  important  modifications  of  the  sur- 
face of  a  country. 

127.  Such  would  take  place,  as  already  remarked,  if  lake  Erie 
was  to  have   its  outlet  cut  backwards  to  its  border  from  the  falls 
of  Niagara  ;:j:  and  if  this  work  of  ages  were  completed,  the  valley 
which  now  constitutes  the  basin  of  the  lake  would  be  traversed 
by  a  large  river.§     The  operations  of  nature,  however,  are  gene- 
rally  gradual ;    and    a  concurrence   of  circumstances  would  be 
requisite  to  cause  the  sudden  evacuation  of  the  contents  of  a 
large  lake. 

128.  A  remarkable  accident  of  this  kind  took  place  in  1818,  in 
consequence  of  the  bursting  of  a  lake  formed  in  the  valley  of 
Bagnes,  in  the  Vallais.  This  valley,  situated  five  leagues  from 
St.  Blanchier,  is  very  narrow  at  one  end,  where  a  ravine  is  formed 
by  mont  Mauvoisin  on  the  south  side,  and  mont  Pleureur  on  the 
north ;  the  latter,  which  is  the  highest,  presenting  a  rocky  sur- 
face above  500  feet  in  altitude,  capped  by  the  immense  glacier  of 
Chedroz.  Large  blocks  of  ice  often  falling  from  these  heights  accu- 
mulate continually  in  the  valley,  through  which  passes  the  river 
D ranee,  fed  by  the  waters  of  more  distant  glaciers.     The  stream 
had  formed  for  itself  a  bed  under  the  mass  of  ice  and  snow ;  but 
in  the  winter  of  1818,  the  glacier,  which  had  been  gradually  in- 
creasing, dammed  up  entirely  the   passage  by  which  the   river 
made  its  exit.     The  waters  were  thus  retained  within  the  valley, 
forming  an  immense  lake,  confined  on  one  side  only  by  the  wall 
of  ice.     On  the  1 4th  of  May  the  lake  was  7200  feet  or  a  mile  and 
one-third  in  length,  and  630  feet  in  breadth,  its  greatest  depth  being 
129.     The  government  of  the  canton  of  Vallais,  to  prevent  as  far 

What  kind  of  rock  constitutes  the  upper  part  of  the  White  mountain  ? 
How  may  violent  effects  of  water  be  seen  to  take  place  on  the  removal 
of  its  barriers  ? 

What  example  of  this  kind  happened  in  the  valley  of  Bagnes? 

*  Abstract  of  an  Account,  of  the  White  Mountains.  By  Jacob  Bigelow, 
M.  D. — Brande's  Journal  of  Science,  vol.  ii.  p.  393. 

t  Idem,  p.  397. 

\  In  1831,  we  happened  to  be  present  at  the  Falls  of  Niagara,  and  to 
witness  the  descent  of  a  lars:e  mass  of  rock  from  beneath  the  shelving  cliff 
uader  which  visiters  pass  to  arrive  beneath  the  sheet  of  water. — ED. 

$  Se.e  De  Ja  Beche's  Geolog.  Man.  pp.  59 — 61. 


LAKE  OF  NEUFCHATEL.  343 

as  possible  the  ravages  to  be  apprehended  from  a  sudden  inunda- 
tion, had  an  artificial  gallery  700  feet  in  length,  cut  through  the 
ice,  50  feet  below  the  level  of  the  lake.  This  was  completed  in 
time  to  carry  off  a  large  portion  of  the  water,  reducing  it  from 
about  800,000,000  to  530,000,000  cubic  feet.  But  on  the  approach 
of  the  hot  season,  the  central  part  of  the  remaining  wall  of  ice 
gave  way,  with  a  tremendous  crash,  and  the  lake  was  emptied  in 
half  an  hour,  the  flood  sweeping  away  trees  houses,  bridges,  and 
large  masses  of  rock,  some  of  which  were  of  enormous  size.  It 
desolated  the  plains  of  Martigny,  and  afterwards  passed  on  with 
diminishing  velocity  till  it  entered  the  Rhone,  on  whose  current 
the  bodies  of  some  men  who  had  been  drowned  were  carried 
a  distance  of  about  thirty  miles,  to  the  further  side  of  the  lake  of 
Geneva,  near  Vevay. 

129.  In  1595,  an  inundation  took  place  in  the  valley  ofBagnes, 
owing  to  precisely  the  same  cause  with  that  of  1818,  it  destroyed 
the  villages  situated  on  the  banks  of  the  Drance,  and  carried  away 
a  great  part  of  the  town  of  Martigny.* 

130.  When  deposits  take  place  of  sand  and  other  substances, 
transported  by  rivers  into  the  basins  of  lakes,  the  effects  will  be 
analogous  to  those  before  noticed,  as  resulting  from  depositions 
on  the  bed  of  the  sea.     Islands  in  general  will  first  appear  above 
the  surface  of  the  water,  which  uniting  with  each  other,  and  then 
with  the  land  constituting  the  banks  of  the  lake,  must  at  length 
produce  a  level  tract,  intersected  by  the  stream  to  whose  action  it 
owed  its  origin.     Such  formations  must  in  most  instances  be  gra- 
dual and  protracted  ;   but  indications  of  their  progress  have  fre- 
quently been  observed. 

131.  De  Saussure,  in  his  "Travels  among  the  Alps,"  mentions 
having  obtained  several  very  fine  views  of  the  lake  of  Neufchatel. 
"  We  were  struck,"  says  he,  "  upon  first  beholding  it,  with  the 
great  extent  which  it  must  formerly  have  had  :  for  the  spacious, 
marshy,  and  horizontal  meadows  by  which  it  is  bounded  on  the 
south  west,  have  unquestionably  been  at  some  period  covered  by 

What  effect  resulted  from  the  discharge  of  the  water  from  that,  valley  ? 

What  previous  occurrence  of  the  same  kind  is  recorded  as  having  hap- 
pened at  the  same  place  ? 

What  is  the  natural  effect  of  the  flowing  of  streams  into  lakes  or  inland 
seas  ? 

What  observation  did  Saussure  make  on  the  extent  of  Neufchatel  lake? 

*  Brande's  Journal  of  Science,  vol.  v.  pp.  372 — 374 ;  and  Edinb.  Philos. 
Journ.,  vol.  i.  p.  187,  &c. 

Mr.  Bakewell,  in  noticing  the  catastrophe  of  1818,  says:  "  From  the  quan- 
tity of  mud  and  stones  which  the  current  bore  along,  it  resembled  a  moving 
mass  of  stones  and  earth.  An  English  gentleman,  who  was  descending 
die  valley  at  the  time,  observed  his  horse  exhibit  by  his  motions  great  tre- 
pidation, of  which  he  could  not  discover  the  cause,  until  a  loud  rushing 
noise  occasioned  him  to  look  back,  when  he  beheld  what  appeared  like  a 
wall,  filling  up  the  bottom  of  the  valley,  and  advancing  rapidly  towards 
him.  He  instantly  alighted,  and  scrambled  up  the  adjacent  rocks,  leaving 
his  horse  to  his  fate." — Introd.  to  Geof.,  p.  508. 


344  GEOLOGY. 

its  waters.  We  shall  have  occasion  to  make  the  same  remark 
with  respect  to  the  other  bank  of  the  lake."*  The  alluvial  land 
here  mentioned,  according  to  De  Luc,  still  increases,  but  now 
very  slowly ;  the  first  deposits,  on  the  contrary,  accumulated 
rapidly  from  the  abundance  of  debris  encountered  by  the  waters 
originally,  when  likewise  their  courses  were  less  tortuous  than  at 
present.f 

132.  The  higher  part  of  the  lake  of  Como  is  nearly  filled  up 
by  the  detritus  transported  by  the  Adda  and  Mera.:f:     The  former 
has  divided  the  lake  into  two ;  the  smaller  portion  (known  by  the 
name  of  lago  di  Mesola)  being  so  shallow,  from  the  united  de- 
posit of  the  two  rivers  and  some  torrents,  that  aquatic  plants  grow 
through  the  water  on  the  eastern  part;  while  on  the  western,  in 
which  there  is  a  greater  depth,  the  process  of  filling  up  is  hasten- 
ed by  means  of  stones,  detached  in  such  numbers,  in   particular 
seasons  of  the  year,  from  the  heights  on  that  side,  that  a  passage 
in  a  boat  beneath  the  cliffs  becomes  exceedingly  hazardous. "§ 

133.  The  accumulation  of  solid  matter  in  the  basins  of  lakes, 
and  the  gradual  transformation  of  lakes  into  rivers,  are  well  de- 
scribed by  Professor  Playfair,  and  exemplified  in  the  progressive 
changes  observable  in  the  lakes  of  Westmoreland  and  C umber- 
land.  j|    But  it  is  unnecessary  to  multiply  instances  of  such  pheno- 
mena,  the  nature  of  which  may  be  sufficiently  understood  from 
the  details  already  given. 

134.  The  destructive  effect  of  water  in  the  degradation  of  the 
surface  of  the  earth,  is  obvious  in  the  occurrence  of  those  phe- 
nomena called  landslips.    Accidents  of  this  sort  may  be  produced 
by  the  weight  of  quantities  of  water  percolating  through  porous 
strata,  and  collecting  in  communicating  cavities  at  various  depths, 
in  consequence  of  which  thick  masses  of  rock,  may  be  disrupted 
by  the  force  of  hydrostatic  pressure.^"    Water  also  may  find  its 
way  to  beds  of  argillaceous  or  calcareous  earth,  between  rocks 
composed  of  denser  matter,  highly  inclined,  and  producing  dis- 
integration of  the  connecting  strata,  the  superincumbent  masses 
may  fall  by  their  own  weight.   Circumstances  of  this  kind  have 
repeatedly  occurred  in  different  parts  of  the  Alps. 

135.  In  1248,  a  portion  of  morit  Grenier,  south  of  Chamery,  in 

What  evidence  does  lake  Como  furnish  of  a  change  of  extent  from  de- 
trition of  river  banks? 

Into  what  are  lakes  converted  when  their  basins  have  become  choked 
up  with  detritus  and  other  alluvial  matter? 

How  are  landslips  produced  ? 

In  what  manner  may  water  assist  in  producing  them  ? 

*  Voyages  dans  les  Alpes,  sect.  390. 

t  Treatise  on  Geology,  p.  160. 

t  See  Sections  and  Views  illustrative  of  Geological  Phenomena,  by  Mr. 
De  la  Beche,  pi.  31. 

$  De  la  Beche's  Geol.  Man.,  p.  53. 

II  See  Illustrations  of  the  Huttonian  Theory  of  the  Earth,  Edinb.  1802, 
p.  357. 

1T  See  Scientific  Class  Book,  part  i.,  p.  133.  (Hydr.  No.  32.) 


LANDSLIPS.  345 

Savoy,  fell,  and  buried  five  parishes,  including  the  town  and 
church  of  St.  Andrew,  the  ruins  covering  the  space  of  about  nine 
square  miles,  called  les  Jlbymea  de  Myans ,-  which,  notwithstand- 
ing the  lapse  of  so  long  a  period,  still  exhibits  a  singular  scene 
of  desolation.*  Pleurs,  a  considerable  town  in  the  Grisons,  with 
the  neighbouring  village  of  Schelano,  was  thus  destroyed,  August 
26,  1618.  On  that  day  an  inhabitant  entered  the  town,  and  told 
his  neighbours  that  he  had  seen  the  mountains  cleaving;  but  he 
was  only  laughed  at  for  his  information.  However,  in  the  even- 
ing, the  town  and  all  its  inhabitants,  except  this  person,  were 
overwhelmed  by  the  fall  of  a  vast  mass  of  rock  from  the  south 
side  of  the  mountain  of  Corto,  which  had  been  loosened  by  per- 
colated water. 

136.  A  part  of  the  mountain  near  Servoz,  on  the  road  to  Cha- 
mouni,  fell  down  in  1751.     The  descent  of  the  mass  did  not  take 
place  in  this  case  at  once,  as  happened  at  mont  Grenier ;  for  the 
mountain,  consisting  of  a  succession  of  beds  of  limestone  resting 
on  sandstone  and  extremely  fragile  schist,  gave  way  by  degrees. 
For  many  days  a  succession  of  reports,  like  those  of  cannon, 
announced  the  continual  falling  of  the  rocks,  day  and  night;  and 
the   air  was  filled  with  vast  volumes  of  black  dust,  extending 
twenty  miles.     The  rocks  still  appear  to  be  subject  to  the  con- 
stant action  of  rain  ;  and  in  1821  Mr.  Bakewell  noticed  appearances 
indicating  the  probability  of  a  renewal  of  the  catastrophe  of  1751. 

137.  Three  villages,   with  the  inhabitants,  were  entirely  de- 
stroyed in  1772,  when  the  mountain  of  Pitz  fell,  in  the  district  of 
Treviso,  in  the  Venetian  territory.f     The  fall  of  the  mountain 
called  Rossberg  or  Ruffiberg,  in  Switzerland,  took  place  Septem- 
ber 2,  1806.     It  is  5196  feet  above  the  level  of  the  sea,  and  is 
situated  opposite  to  mont  Righi.     At  five  in  the  evening,  the 
Knippenhuhl  rock,  which  formed  the  summit  of  the  mountain, 
was  on  a  sudden  detached  from  its  station,  carrying  with  it  part 
of  the  mountain  a  few  feet  in  thickness  on  the  western  side,  and 
about  280  feet  on  the  eastern  side,  which  rolling  into  the  valley 
that  separates  the  lake  of  Zug  from  that  of  Lauwertz,  overwhelmed 
the   entire  villages  of  Goldan,  Rothen,  Busingen,  Huezloch,  and 
three-fourths  of  that  of  Lauwertz.     The  fall  of  a  portion  of  the 
mountain  into  the  lake  of  Lauwertz,  filled  up  about  one-fourth 
part  of  it,  and  caused  such  an  inundation  as  overthrew  a  number 

What  appearance  is  now  presented  where  the  fall  of  mont  Grenier  took 
place  ? 

What  other  similar  occurrences  have  taken  place  among  the  Alps? 
How  did  the  fall  of  Chamouni  differ  from  others  in  the  same  region  ? 
To  what  is  the  difference  attributed  ? 
What  peculiar  circumstances  accompanied  the  fall  of  the  Rossberg? 

*  See  BakewelFs  Introduction  to  Geology,  Silliman's  edition,  page  315, 
where  the  account  of  the  fall  of  mont  Grenier  is  illustrated  by  a  cut,  re- 
presenting the  present  state  of  the  Abymes  de  Myans. 

t  Malte  Brun's  Geography,  vol.  i,  p.  435. 


346  GEOLOGY. 

of  houses,  chapels,  mills,  and  other  buildings,  on  the  southern 
shore  of  the  lake.  Enormous  masses  of  rock  are  said  to  have 
been  carried  through  the  air  to  prodigious  distances.  The  rocks 
in  falling  brought  down  great  quantities  of  earth,  together  with 
large  blocks  of  flint,  which  were  thrown  on  the  opposite  bank  of 
the  lake,  to  the  height  of  from  80  to  100  feet. 

138.  In  the  villages  overwhelmed  not  an  individual  escaped  de- 
struction ;  and  eight  or  nine  hundred  persons  fell  the  victims  of  this 
disaster.     The  structure  of  the  Rossberg  sufficiently  accounts  for 
the  occurrence,  which  General  Pfiffer  is  reported  to  have  predicted 
twenty  years  previously.     Its  upper  part  is  composed  of  beds 
of  a  compound  rock,  formed  from  the  debris  of  the  Alps  at  an 
antecedent  geological  period;  and  these  being  porous,  admitted 
the  percolation  of  water  arising  from  rain  and  melted  ice  and 
snow,  which  softening  the  clay  between  the  more  solid  strata, 
inclined  at  an  angle  of  about  45°,  a  slide  took  place,  and  they 
were  precipitated  into  the  valley  below.* 

139.  A  large  portion  of  mountain  consisting  of  rocks  and  soil, 
covered  with  fir-trees,  separated  from  the  highest  region  of  the 
Alps,  on  the  4th  of  April,  1818,  near  the  village  of  Soncebos,  in 
the  valley  of  St.  Imier,  in  Switzerland,  and  covered  with  its  stu- 
pendous wreck  more  than  three  hundred  paces  of  the  great  road 
to  Brienne.    A  party  of  travellers  witnessed  this  terrific  catastro- 
phe who,  had  they  been  a  few  moments  later,  would  have  been 
its  victims. f 

140.  Partial  alterations  of  the  surface  of  a  country  may  be 
produced    by  deluges  of  mud,   owing  to  the   bursting  of  peat- 
mosses and  bogs.     In  December,  1772,  Solway  moss  having  been 
filled  with  water  during  heavy  rains,  rose  to  an  unusual  height 
and  then  burst.     A  stream  of  black  thick  mud  flowed  over  the 
plain,  like  a  current  of  lava;  overwhelming  some  cottages,  and  co- 
vering 400  acres  of  land  ;  but  fortunately  without  occasioning  the 
loss  of  human  life.     The  highest  parts  of  the  original  moss  sub- 
sided about  twenty-five  feet,  and  the  lowest  part  of  the  country 
submerged  was  full  fifteen  feet  deep.:J: 

141.  A  similar  phenomenon  occurred  more  recently  on  the  con- 
fines of  Yorkshire  and  Lancashire,  England.    On  the  2d  of  Sep- 
tember, 1824,  at  Haworth,  five  miles  south  of  Keighley,  in  the 
West  Riding  of  the  county  of  York,  and  on  the  borders  of  Lan- 
cashire, about  six  o'clock  in  the  evening,  a  part  of  the  highlands 
on  the  Stanbury  moor  opened  into  a  chasm,  and  sunk  to  the  depth 
of  six  yards,  in  some  places  exhibiting  a  ragged  appearance,  and 

How  is  that  event  to  be  explained  ? 

By  what  other  mode  may  the  surface  of  a  country  be  covered  with 
earthy  deposits  ? 
Describe  the  occurrence  at  Solway  moss  ? — At  Haworth  ? 

*  Nicholson's  Journal  of  Natural  Philosophy,  8vo.  vol.  xv.  pp.  150 — 152. 
t  Brande's  Journal  of  Science,  vol.  v.  p.  377. 
J  Lyell's  Principles  of  Geology,  vol.  iii.  p.  137. 


DESTRUCTIVE  ACTION  OF  FROZEN  WATER.  347 

forming  two  principal  cavities — the  one  was  about  two  hundred 
yards,  and  the  other  not  less  than  six  hundred  yards  in  circumfe- 
rence. From  these  hollows  issued  two  immense  volumes  of  muddy 
water,  which  uniting  at  the  distance  of  upwards  of  one  hundred 
yards  from  their  sources,  constituted,  for  about  two  hours,  an 
overwhelming  flood  from  forty  to  fifty  (sometimes  seventy)  yards 
in  width,  and  seldom  less  than  four  yards  in  depth.  This  dark 
slimy  mixture  of  mud  and  water  followed  the  course  of  a  rivulet, 
overflowing  its  banks  for  twenty  or  thirty  yards  on  each  side,  and 
to  the  distance  of  seven  or  eight  miles  from  the  immediate  erup- 
tion ;  all  this  way  there  was  deposited  a  black  moorish  substance, 
varying  from  eight  to  thirty-six  inches  in  depth,  and  mixed  occa- 
sionally with  sand  and  rocky  fragments,  pieces  of  timber,  and  up- 
rooted trees,  which  had  been  borne  along  by  the  impetuous  tor- 
rent. 

142.  This  heavy  and  powerful  stream  broke  down  one  solid 
stone  bridge,  made  breaches  in  two  others,  clogged  up  and  stop- 
ped several  mills,  laid  flat  and  destroyed  many  fields  of  corn,  and 
overthrew  to  the  foundation  several  hedges  and  walls.      In  its 
course  it  entered  the  houses,  floating  "the  furniture  about  to  the 
astonishment  and  terror  of  the  inhabitants.  At  the  time  of  the  erup- 
tion, the  clouds  were  copper-coloured  and  lowering ;  the  atmosphere 
was  strongly  electric,  and  unusually  close  and  sultry.  There  was 
at  the  same  time  loud  and  frequent  thunder,  with  much  zigzag 
lightning,  peculiarly  flaring  and  vivid.    An  hour  before  there  was 
scarcely  a  breath  of  air  stirring,  but  the  wind  quickly  rose  to  a 
hurricane  ;  and  after  blowing  hard  from  six  to  eight  o'clock,  sunk 
again  into  a  profound  calm,  at  which  time  the  heavy  rain,  which 
had  continued  all  the  while,  ceased,  and,  with  the  exception  of  a 
few  floating  clouds,  the  sky  was  very  serene.    Part  of  the  torrent 
of  mud  passed  into  the  river  Aire,  rendering  its  stream  turbid  at 
Leeds,  and  causing  the  destruction  of  great  quantities  offish. 

143.  A  still  later  inundation,  from  the  bursting  of  a  peat-moss, 
happened  in  the  county  of  Sligo,  in  Ireland.   After  a  sudden  thaw 
of  snow,  in  January,  1831,  the  bog  between  Bloomfield  and  Gee- 
vah  gave  way,  and  a  black  deluge  flowing  in  the  direction  of  a 
smalt  stream,  swept  along  heath,  timber,  mud,  and  stones,  and 
overflowed  several  meadows  and  tracts  of  arable  land.     Passing 
through  a  piece  of  bog,  the  flood  traced  a  wide  and  deep  ravine, 
and  carried  away  completely  two  hundred  yards  of  a  solid  road.* 
The  sudden  removal  of  large  tracts  of  land  on  the  banks  of  the 
Mississippi  is  an  event  of  frequent  occurrence.     The  many  bends, 
"  cut  offs"  and  lagoons,  in  that  region,  are  the  consequences  of 
this  aqueous  action. 

What  other  phenomena  acccompanied  the  latter  event? 

What  example  of  the  bursting  of  a  bog  has  been  observed  in  Ireland  ? 

What  remarkable  action  takes  place  along  the  line  of  the  Mississippi  ? 

*  Lyell's  Principles  of  Geology,  u.  a. 


348  GEOLOGY. 

144.  The  destructive  action  of  water  in   consequence  of  its' 
congelation  by  cold,  is  sometimes  exhibited  on  a  very  extensive 
scale.     In  cold  climates,  the  disintegration  of  rocks  is  caused  by 
the  freezing  of  water,  which  having  insinuated  itself  into  crevices 
in  its  utmost  state  of  condensation,  afterwards  expands  in  the  act 
of  forming  ice.     Loud  reports,  owing  to  the  rifting  of  rocks  from 
this  cause,  frequently  attest  the  magnitude  and  violence  of  the 
effects  produced  ;  and  thus  large  masses  of  rock  with  superincum- 
bent glaciers  are  torn  from  the  summits  and  sides  of  mountains, 
and  fall  in  desolating  avalanches  into  the  vales  below.    When 
larg^e  rivers  are  frozen  and  a  sudden  thaw  comes  on,  great  blocks 
of  ice  floating  on  the  swollen  current  may  be  driven  against  its 
banks  and  cut  away  from  them  considerable  portions,  which  fall- 
ing into  the  water  may  obstruct  its  passage  and  cause  floods,  or 
even  alter  the  course  of  a  stream.     The  destructive  operations  of 
icebergs,  when  drifted  against  maritime  cliffs  and  precipices,  may 
obviously  be  productive  of  considerable  modifications  of  the  coast 
of  a  country,  causing  the  fall  of  vast  masses  of  rock  and  soil,  to 
be  afterwards  disintegrated  and  scattered  by  the  waves  of  the 
sea. 

145.  The  influence  of  waves,  breakers,  and    ocean  currents, 
both  in  the  degradation  of  land  and  in  the  formation  of  new  strata 
beneath  the  water,  contributes,  perhaps,  more  than  any  other  cause, 
to  the  alterations  that  are  taking  place  on  the  superfices  of  the* 
earth.     Their  destructive   effect   is   more   immediately   obvious 
when  they  act  on  cliffs  composed  more  or  less  of  soft  materials, 
and  rising  somewhat  abruptly  above  the  level  of  the  sea ;  and 
hence  the  configuration  of  coasts  will    greatly  depend    on   the 
relative   hardness  of  the  rocks    of  which   they  are   composed. 
Thus  the  waves  sometimes  form  bays  or  inlets  by  washing  away 
portions  of  land  ;  and  where  their  action  is  resisted  by  more  dense 
materials,  they  produce  only  a  partial  effect :  yet  the  most  solid 
rocks  may  in  time  give  way,  and  the  progress  of    destruction 
influence  the  formation  of    ocean   caves,  or   produce   detached 
masses  rising  from  the  bosom  of  the  deep,  and  presenting  a  variety 
of  fantastic  forms. 

146.  Dr.  Hibbert,  enumerating  the  effects  of  the  waves  on  the- 
coasts  of  the  Shetland  islands,  says  :  "The  most  sublime  scene  is 
where  a  mural  pile  of  porphyry,  escaping  the  process  of  disintegra- 
tion that  is  devastating  the  coast,  appears  to  have  been  left  as  a 
sort  of  rampart  against  the  inroads  of  the  ocean ;  the  Atlantic, 
when  provoked  by  wintry  gales,  batters  against  it  with  all  the 
force  of  real  artillery,  the  waves  having,  in  their  repeated  assaults, 
forced  themselves  an  entrance.    This  breach,  named  the  grind  of 
the  Navir,  is  widened  every  winter  by  the  overwhelming  surge 

How  may  we  explain  the  falling  of  masses  of  rock  from  mountains  in 
lime  of  severe  frosts? 

How  shall  we  account  for  the  change  in  form  of  maritime  cliffs? 
What  is  the  most  active  cause  of  changes  in  the  earth's  surface  ? 
On  what  does  the  configuration  of  coasts  depend  ? 


EFFECTS  OF  WAVES  AND  BREAKERS.  349 

that,  finding  a  passage  through  it,  separates  large  stones  from 
its  sides,  and  forces  them  to  a  distance  of  no  less  than  180  feet. 
In  two  or  three  spots,  the  fragments  that  are  detached  are  brought 
together  in  immense  heaps,  that  appear  as  an  accumulation  of 
cubical  masses,  the  product  of  some  quarry."* 

147.  The  same  writer  gives  instances  of  the  destruction  of 
islands,  "  until  at  last  they  become  mere  clusters  of  rocks,  the  last 
shreds  of  masses  once  continuous."     Such  was  the  origin  of  the 
granitic  rocks  called  the  Drongs,  between  Papa  Stour  arid  Hills- 
wick  Ness  :  and  of  a  singular  cluster  of  rocks,  of  a  similar  nature, 
to  the  south  of  the  latter  island. 

148.  The  power  of  the  sea  when  agitated  is  especially  remark- 
able in  overturning  and  drifting  vast  blocks  of  solid  rock.  Steven- 
son states  that  at  the  depth  of  two  hundred  feet  the  action  of  the 
sea  is  sufficient  to  break  rocks  in  pieces,  and  throw  them  upon 
the  coasts  in  masses  of  various  forms  and  dimensions.     He  ob- 
serves that  "numerous  proofs  of  the  sea  being  disturbed  to  a 
considerable  depth  have  occurred  since  the  erection  of  the  Bell 
Rock  lighthouse,  situated  upon  a  sunken  rock  in  the  sea,  twelve 
miles  off  Arbroath,   in  Forfarshire.     Some   driftstones   of  large 
dimensions,  measuring  upwards  of  thirty  cubic  feet,  or  more  than 
two  tons  weight,  have,  during  storms,  been  often  thrown  upon  the 
rock  from  the  deep  water.     These   large  boulderstones   are   so 
familiar  to  the  lighthouse-keepers  at  this  station,  as  to  be  by  them 
termed  travellers."* 

149.  The  effects  of  the  more  protracted  action  of  waves  and 
breakers  is  abundantly  remarkable  on  various  parts  of  the  shores 
of  England,  and  in  few  situations  more  so  than  on  those  of  Suffolk. 
The  gradual  destruction  of  the  once  extensive,  flourishing,  and 
populous  city  of  Dunwich,  has  been  noticed  by  several  writers. 
"  Gardner,  in  his  history  of  the  borough,  published  in  1754,  shows, 
by  reference  to  documents,  beginning  with  Domesday  Book,  that 
the  cliffs  at  Dunwich,  Southwold,  Eastern,  and  Pakefield,  have 
been  always  subject  to  wear  away. 

150.  "  At  Dunwich  in  particular,  two  tracts  of  land  which  had 
been  taxed  in  the  eleventh  century,  in  the  time  of  King  Edward 
the  Confessor,  are  mentioned  in  the  Conqueror's  survey,  made  but 
a  few  years  afterwards,  as  having  been  devoured  by  the  sea.  The 
losses,  at  a  subsequent   period,  of  a  monastery — at  another  of 
several  churches — afterwards  of  the  old  port — then  of  four  hun- 

What  instance  of  the  action  of  waves  on  hard  rocks  has  been  particu- 
larly noticed  ? 

What  changes  are  sometimes  known  to  take  place  in  the  appearance  of 
islands  ? 

What  is  meant  by  the  term  "  travelling  rocks  ?" 

What  event  proving  the  gradual  encroaching  of  the  sea  on  the  land  is 
recorded  ? 

*  Description  of  the  Shetland  Islands,  Edinb.  1822,  p.  528. 
t  See  Memoirs  of  the  Wernerian  Society,  vol.  iii 
2G 


350  GEOLOGY. 

dred  houses  at  once — of  the  church  of  St.  Leonard,  the  high  road, 
town-hall,  the  gaol,  and  many  other  buildings,  are  mentioned, 
with  the  dates  when  they  perished.  It  is  stated  that  in  the  six- 
teenth century,  not  one  quarter  of  the  town  was  left  standing;  yet 
the  inhabitants,  retreating  inland,  the  name  was  preserved,  as  has 
been  the  case  with  many  other  ports,  when  their  ancient  site  has 
been  blotted  out. 

151.  "  There  is,  however,  a  church  of  considerable  antiquity  still 
standing,  the  last  of  twelve  mentioned  in  some  records.    In  1740, 
the  laying  open  of  the  churchyard  of  St.  Nicholas  and  St.  Francis, 
in  the  sea  cliffs,  is  well  described  by  Gardner,  with  the  coffins  and 
skeletons  exposed  to  view — some  lying  on  the  beach,  and  rocked 

'  In  cradle  of  the  rude  impetuous  surge.' 

Of  these  cemeteries  no  remains  can  now  be  seen.  Ray  also  says, 
'That  ancient  writings  make  mention  of  a  wood  a  mile  and  a  half 
to  the  east  of  Dunwich,  the  site  of  which  must  at  present  be  so 
far  within  the  sea.'*  This  city,  once  so  flourishing  and  populous, 
is  now  a  small  village,  writh  about  twenty  houses,  and  one  hun- 
dred inhabitants. "f 

152.  The  action  of  tides  and  currents  must  be  taken  into  the  ac- 
count, in  estimating  the  influence  of  the  sea  in  producing  modifica- 
tions of  the  surface  of  the  globe.     Tides  are  chiefly  felt  on  the 
coasts,  and  their  effects  must  be  in  a  great  degree  similar  to  those 
above  described ;  but  the  operation  of  currents  may  cause  a  variety 
of  changes  in  the  bed  of  the  sea,  in  some  places  scooping  out  hol- 
lows, and  in  others  heaping  up  wide  tracts,  or  where  from  particular 
causes  their  direction  has  undergone  alteration,  sweeping  away 
and  dispersing  the  sand-beds  produced  by  former  currents.  There 
are  currents  of  various  descriptions,  the  most  important  being  those 
which  appear  to  be  permanent.     Such  are  the  Gulf  stream,  and 
other  branches  of  the  great  equinoctial   current;    the   Polar   or 
Greenland   current,  flowing  strongly  through  Hudson's  bay  and 
Davis's  strait ;  a  current,  which  sets  eastward  into  the  Mediter- 
ranean sea;  and  another  that  flows  out  of  the  Baltic,  into  the  Ger- 
man ocean.      Besides  these,  there  are  a  considerable  number  of 
periodical  and  temporary  currents,  the   transporting  power   and 
effects  of  which  must  vary  with  circumstances. 

153.  Such  are  some  of  the  more  general  and  widely-operating 
causes  of  the  modifications  of  the  earth's  surface,  which  have 
taken  place  within  the  period  of  historical  record ;  but  there  are 
others,  which  are  rather  of  a  local  nature,  though  their  effects  may 
in  some  cases  be  very  extensive,  and  are  often  extremely  striking 

What  has  preserved  the  name  of  Dunwich  since  its  site  has  been  in- 
gulphed  ? 

What,  besides  the  force  of  the  winds,  is  effective  in  causing  maritime 
detrition  ? 

*  Consequences  of  the  Deluge — Physico-Theological  Discourses, 
t  Lyell's  Principles  of  Geology,  vol.  i.  pp.  403,  404. 


CALCAREOUS  DEPOSITS  FROM  HOT  SPRINGS.  351 

and  important.  Among  these  are  chemical  deposits  from  fresh 
water,  marine  formations,  either  from  chemical  deposition  or  the 
work  of  coral  polypes  ;  and  volcanos  and  earthquakes.  All  these 
are  highly  interesting,  and  might  furnish  materials  for  several 
volumes  ;  but  among  the  numerous  topics  that  remain  to  be  con- 
sidered, they  can  here  only  obtain  a  passing  notice. 

154.  Some  thermal  springs   contain   siliceous   earth,   held   in 
solution  by  their  waters,  and  deposited  on  cooling.     Such  are  the 
Geysers  in  Iceland,  previously  mentioned.     Their  deposits  extend 
over  an  area  of  about  half  a  mile  in  diameter ;  and  from  the  depth 
of  a  cleft  near  the  Great  Geyser,  the  siliceous  matter  appears  to 
be  more  than  twelve  feet  in  thickness.  The  hot  springs  of  Furnas, 
in  the  volcanic  district  of  St.  Michael,  one  of  the  Azores,  deposit 
large  quantities  of  clay  and  silex,  enveloping  grass,  leaves,  and 
other  vegetable  bodies.  Dr.  Webster  found  "  branches  of  the  ferns, 
which  now  flourish  in  the  island,  completely  petrified,  preserving 
the  same  appearance  as  when  vegetating,  excepting  the  colour, 
which  is  now  ash-gray.     Fragments  of  wood  occur,  more  or  less 
changed ;  and  one  entire  bed,  from  three  to  five  feet  in  depth,  is 
composed  of  the   reeds   so  common   in   the   island,  completely 
mineralized,  the  centre  of  each  joint  being  filled  with  delicate  crys- 
tals of  sulphur."*      The  deposits  are  both  abundant  and  various, 
frequently  forming  horizontal  strata.     In  the  cavities  of  the  de- 
posits occur  siliceous  stalactites  often  two  inches  long,  and  covered 
with  small  brilliant  quartz  crystals.  Compact  masses,  broken  from 
various  causes  and  cemented  again  by  siliceous  matter,  form  brec- 
cia, the  elevations  of  which,  in  some  places,  Dr.  Webster  estimates 
at  more  than  thirty  feet. 

155.  There  are  hot  springs  at  Washita,  in  Arkansas  territory,  in  a 
district  exhibiting  some  traces  of  extinct  volcanos, f  which  deposit 
a  very  copious  sediment,  consisting  of  silex,  lime,  and  iron ;  and 
the  thermal  springs  of  Pinnarkoon  and  Loorgootha,  in  the  East 
Indies,  contain  silica  and  various  salts  of  soda. 

156.  Travertin,  or  calcareous   tufa,  is   another   deposit   from 
springs ;  and  though  it  is  most  common  in  limestone  districts  it  is 
by  no  means  confined  to  them,  occurring  indiscriminately  in  all 
rock  formations.     In  Auvergne,  in   France,  where   the  primary 
rocks  are  unusually  destitute  of    limestone,  springs  abundantly 
charged  with  carbonate  of  lime  rise  up  through  the  granite  and 
gneiss.  Again,  in  the  valley  of  the  Elsa,  which  skirts  the  Apennines 
in  Italy,  are  innumerable  springs,  which  have  thrown  down  such 

What  change  in  the  structure  of  the  earth's  surface  is  effected  by  the 
agency  of  animals  ? 

What  change  is  produced  by  the  action  of  hot  springs? 
What  examples  illustrate  this  kind  of  action  ? 
What  is  the  chemical  nature  of  travertin  ? 
In  what  localities  has  it  been  deposited  ? 

*  Edinb.  Philos.  Journ..  vol.  vi. 

t  See  Featherstonbaugh's  Geological  Report,  pp.  63  to  69. 


352  GEOLOGY. 

calcareous  precipitates,  that  the  whole  ground  in  some  parts  of 
Tuscany  is  coated  with  travertin,  and  sounds  hollow  under  foot. 
A  most  striking  instance  of  the  rapid  deposit  of  carbonate  of  lime 
from  thermal  waters  may  be  observed  in  the  hill  of  San  Vignone, 
near  Radicofani,  and  a  few  hundred  yards  from  the  high  road  be- 
tween Sienna  and  Rome.  A  large  mass  of  travertin  descends  the 
hill  from  the  point  whence  the  spring  issues  to  the  bank  of  the 
river  Orcia,  a  distance  of  250  feet,  "forming  a  mass  of  varying 
thickness,  but  sometimes  200  feet  in  depth  ;  and  on  the  other  side 
of  the  hill  a  similar  deposit  extends  about  half  a  mile  in  parallel 
strata,  one  of  which  is  15  feet  thick,  and  constitutes  excellent 
building  stone.  Large  masses  of  travertin  have  also  been  deposited, 
forming  escarpments  along  the  borders  of  the  stream  into  which 
the  waters  of  the  Washita  hot  springs  descend. 

157.  Thermal    springs,  which    yield   calcareous  deposits,  are 
found  in  several  parts  of  Italy,  as  the  famous  baths  of  San  Filippo, 
on  a  hill  a  few  miles  from  that  above  mentioned ;  the  Bulicami,  or 
hot  baths,  in  the  vicinity  of  Viterbo ;  a  thermal  spring,  lately  dis- 
covered near  Civita  Vecchia,  which  forms  alternate  beds  of  a  yel- 
lowish travertin,  and  a  white  granular  rock,  resembling  statuary 
marble;  the  lake  of  Solfatara,  in  the  Campagna,  between  Rome 
and  Tivoli ;  and  calcareous  formations   are  taking  place  in  the 
waters  of  the  river  Velino,  at  Terni ;  and  in  those  of  the  Anio, 
which  produces  the  travertin  of  Tivoli.*   Calcareous  deposits  from 
springs  have  been  noticed  in  Bohemia.  Hungary,  Mount  Caucasus, 
Persia,  and  in  various  other  parts  of  the  world.     Mr.  Mantell 
mentions  an  incrusting  or  lapidescent  spring,  at  Pounceford,  in 
Sussex  ;f  and  such  occur  in  Gloucestershire,  and  in  other  districts 
of  England,  where  there  are  formations  of  limestone. 

158.  Precipitates  of  carbonate  of  lime  are  produced  from  the 
waters  of  some  lakes;  but  there  are  others  which  yield  deposits 
of  a  different  nature,  though  on  a  comparatively  contracted  scale. 
Bog-iron  ore  is  sometimes  found  at  the  bottom  of  lakes  and  peat- 
mosses;  and  its  origin  is  somewhat  problematical.    "It  has  been 
suggested  that  iron,  being  soluble  in  acids,  may  be  diffused  through 
the  whole  mass  of  vegetables  when  they  decay  in  a  bog,  and  may, 
by  its  superior  specific  gravity,  sink  to  the  bottom,  and  be  there 
precipitated   so  as  to  form  bog-iron  ore ;  or  where  there  is  a  sub- 
soil of  sand  or  gravel,  it  may  cement  them  into  ironstone,  or  fer- 
ruginous conglomerate."^: 

159.  In  salt  lakes  considerable  depositions  of  salt  (chloride  of 
sodium)  take  place;  and  such  collections  of  water  being  dried  up 
or  drained,  the  sides  and  bottoms  of  the  basins  are  found  incrusted 

How  is  the  presence  of  iron  ore  in  lakes  to  be  accounted  for? 
What  causes  the  deposition  of  salt  at  the  bottom  of  salt  lakes  ? 

*  See  Lyell's  Prin.  of  Geol.,  vol.  i.  pp.  296—310. 
t  Geology  of  the  South-East  of  England,  1833,  p.  223. 
t  Lyell's  Prin.  of  Geol.,  vol.  iii.  p.  331.    See  Rev.  Dr.  Rennie's  Essays 
on  Peat,  p.  347. 


MARINE  FORMATIONS.  353 

with  salt,  sometimes  constituting  beds  alternating  with  beds  of 
clay.  In  South  Africa  salt  is  obtained  from  such  natural  basins ; 
and  bay  salt  is  the  product  of  salt-pans  or  basins  formed  by  art. 
On  the  western  side  of  the  Rocky  mountains,  in  about  latitude  42°, 
is  a  salt  lake,  around  which  a  party  recently  found  it  took  them 
forty  days  to  travel.  The  salt  is  believed  to  be  brought  down  by 
the  waters  from  saliferous  rock  strata  in  the  mountains  above. 

160.  Carbonate  of  soda  is  precipitated  in  considerable  quantities 
from  the  waters  of  a  lake  in  Venezuela  ;*  and  similar  deposits 
occur  in  other  places. 

Gypsum,  or  sulphate  of  lime,  which  forms  one  of  the  beds  in 
the  great  Paris  basin,  and  must  therefore  have  been  deposited  most 
copiously  at  some  distant  period,  now  appears  to  be  confined  to  a 
very  few  springs.  Those  at  Baden,  near  Vienna,  which  supply 
the  public  bath,  may  be  cited  as  examples.  Some  of  them  yield 
from  600  to  1000  cubic  feet  of  water  an  hour,  and  throw  down  a 
fine  powder,  consisting  of  a  mixture  of  sulphate  of  lime  with  sul- 
phur and  muriate  of  lime,  (chloride  of  calcium. )f 

161.  In  the  island  of  Trinidad  there  is  an  extensive  pitch-lake, 
the  surface  of  which  in  wet  weather  is  sufficiently  hard  to  sup- 
port heavy  weights ;  but  during  the  heats  it  approaches  to  a  state 
of  fluidity.     This  phenomenon,  together  with   the  existence  of 
springs  of  naphtha  and  asphaltum  in  different  quarters  of  the  globe, 
may  serve  in  some  measure  to  elucidate  the  origin  of  bituminous 
shales,  which  occur  in  the  geological  formations  of  different-ages. 

162.  The  destructive  influence  of  the  waves  of  the  sea  is  fre- 
quently exerted  within  the  range  of  observation,  so  that  we  may 
in  many  cases  be  able  to  appreciate  the   effect  produced    with 
tolerable  accuracy.     But  the  formative  or  constructive  operations 
of  the  ocean,  which  are  carried  on  upon  the  most  extensive  scale, 
are  in  general  entirely  hidden  from  our  view.     We  have  abundant 
reason  to  believe  that  many  of  the  strata  which  compose  the  crust 
of  the  terrestrial  globe  were  formed  by  deposition  from  sea-water, 
and  that  analogous  formations   are   now  in  progress;   but  with 
respect  to  the  latter,  we  are  obliged  to  speculate  in  the  dark,  those 
processes  of  nature  in  general  taking  place  at  unfathomable  depths 
beneath  the  surface  of  the  ocean. 

163.  "  As  dwellers  on  the  land,  we  inhabit  about  a  fourth  part 
of  the  earth's  surface ;  and  that  portion  is  almost  exclusively  the 

What  evidence  have  we  that  sulphate  of  lime  has  been  copiously  de- 
posited from  an  aqueous  solution? 

What  facts  enable  us  to  explain  the  existence  of  bitumen  in  connexion 
with  rocky  strata  ? 

Why  are  we  less  familiar  with  the  processes  of  accumulation  than  with 
those  of  detrition  when  effected  by  the  ocean? 

*  A  curious  account  of  the  manner  in  which  soda  is  collected  from  this 
lake  by  the  Indians,  written  by  M.  Palacio  Faxar,  may  be  found  in  Brande's 
Journ.  of  Science,  vol.  i.  p.  188,  &c. 

t  Lyell's  Prin.  of  Geology,  vol.  i.  p.  311 ;  from  Essai  sur  la  Constitution 
Physique  du  Bassin  de  Vienne,  par  C.  Prevost,  p.  10. 
2  o2 


354  GEOLOGY. 

theatre  of  decay,  and  not  of  reproduction.  We  know,  indeed,  that 
new  deposits  are  annually  formed  in  seas  and  lakes,  and  that  every 
year  some  new  igneous  rocks  are  produced  in  the  bowels  of  the 
earth,  but  we  cannot  watch  the  progress  of  their  formation  ;  and 
as  they  are  only  present  to  our  minds  by  the  aid  of  reflection,  it 
requires  an  effort  both  of  the  reason  and  the  imagination  to  ap- 
preciate duly  their  importance.  It  is  therefore  not  surprising  that 
we  imperfectly  estimate  the  result  of  operations  invisible  to  us ; 
and  that,  when  analogous  results  of  some  former  epoch  are  pre- 
sented to  our  inspection,  we  cannot  recognise  the  analogy.  He 
who  has  observed  the  quarrying  of  a  stone  from  a  rock,  and  has 
seen  it  shipped  for  some  distant  port,  and  then  endeavours  to  con- 
ceive what  land  of  edifice  will  be  raised  by  the  materials,  is  in 
the  same  predicament  as  a  geologist,  who,  while  he  is  confined  to 
the  land,  sees  the  decomposition  of  rocks,  and  the  transportation 
of  matter  by  rivers  to  the  sea,  and  then  endeavours  to  picture  to 
himself  the  new  strata  which  nature  is  building  beneath  the 
waters."* 

164.  The  rocks  formed  under  the  surface  of  the  sea  originated 
either  from  mechanical  deposition,  or  from  chemical  precipitation. 
Those  of  the  former  class  are  numerous,  including  most  of  the 
stratified  rocks  which  inclose  sea-shells,  fragments  of  corals,  and 
other  exuviae  or  bones  of  marine  animals.     Among  those  of  the 
latter  class,  some  geologists  have   reckoned  even   granite, f  the 
origin  of  which,  as  well  as  that  of  all  other  unstratified  rocks  has, 
however,  been  more  generally  ascribed  to  igneous  fusion  and  con- 
solidation.   Most  of  the  calcareous  rocks  containing  marine  shells, 
must  have  been  produced  under  the  influence  of  chemical  affinity  ; 
and  of  this  nature  are  the  formations  which  are  occasionally  ob- 
served to  take  place  on  the  sea-coasts. 

165.  Collections  of  perfect  and  broken  sea-shells  *and  corals  are 
sometimes  consolidated    by  the   precipitation  of  calcareous  and 
ferruginous  matter,  constituting  banks  or  beds  of  considerable  ex- 
tent.   Such  masses  containing  shells  occur  on  various  parts  of  the 
shores  of  Great  Britain.     Similar  conglomerates,  including  both 
shells  and  corals,  are  not  uncommon  around  some  of  the  islands 
in  the  West  Indies.  At  Guadaloupe  human  bones  have  been  found 
imbedded  in  a  rock  of  this  kind,  whence  were  obtained  two  im- 

What  cause  prevents  our  verifying  the  conjectures  which  geologists 
have  formed  in  regard  to  this  subject? 

From  how  many  sources  have  submarine  rocks  derived  their  origin  ? 
In  what  situation  have  human  bones  been  obtained  in  a  fossilized  state? 

*  Lyell's  Prin.  of  Geol.  vol.  i.  pp.  117,  118. 

t  "'The  strata  of  granite,"  says  De  Luc.  "  evidently  produced  by  che- 
mical deposition  from  a  liquid,  form,  as  I  have  said,  the  most  ancient  monu- 
ment of  the  action  of  physical  causes  on  our  globe." — Element.  Treat,  on 
Geol.,  p.  49.  This  writer,  however,  doubtless  imagined  the  primitive 
ocean  (capable  of  holding  in  solution  the  substances  which  constitute 
granite)  to  have  been  a  liquid  of  a  different  nature  from  the  waters  of  the 
present  ocean. 


CORAL  ROCKS  AND  ISLANDS.  355 

perfect  human  skeletons,  one  preserved  at  the  British  Museum, 
and  the  other  in  the  Museum  of  Natural  History,  at  Paris ;  and 
from  the  occurrence  of  these  bones  and  other  circumstances,  may 
be  inferred  the  comparatively  modern  origin  of  the  rock  in  question. 
The  Florida  Keys  abound  in  deposits  of  shells  in  various  states  of 
disintegration  and  subsequent  union  by  cement. 

166.  Among-  the  marine  formations  there  are  few  more  curious 
or  interesting  than  coral  reefs  and  islands,  which  to  a  certain  ex- 
tent are  constructed  by  different  kinds  of  polypiferous  zoophytes,* 
or  minute  animals,  for  which  the  coral  tubes  serve  as  habitations. 
It  has  been  supposed  that  the  coral  rocks  descend  in  perpendicular 
columns  to  the  bed  of  the  ocean,  and  cover  millions  of  acres  of  the 
Pacific  ;f  but  though  the  extent  of  such  formations  is  very  con- 
siderable, it  appears  to  have  been  overrated. 

167.  M.  Chamisso,  who  accompanied  as  a  naturalist  the  expe- 
dition of  discovery  sent  out  by  the  Russian  government,  under  the 
command  of  Captain  Kotzebue,  visited  several  groups  of  coral 
islands,  arranged  in  a  circular  or  oval  form,  with  openings  among 
them  which  afforded  access  to  the  interior  basin.     These  islands 
seemed    to    be    only    the    upper   portions    of    ridges   of  unequal 
heights,  on  the  inside  of  which,  towards  the   basin   or  lagoon, 
where  there  is  still  water,  the  smaller  and  more  delicate  kinds  of 
polypes  carry  on  their  operations,  while  the  stronger  species  live 
and  work  on  the  exterior  margin  of  the  bank,  against  which  a 
great  surf  usually  breaks. 

168.  These  creatures  leave  off  building  as  soon  as  their  struc- 
tures reach  such  a  height  as  to  be  left  almost  dry  at  the  lowest 
ebb  of  the  tide.     A  continuous  mass  of  solid  stone  is  seen  com- 
posed of  shells  of  molluscs  and  echini,  with   their    broken-off 
prickles  and  fragments  of  coral  cemented  by  calcareous  matter. 
The  ridge  is  raised  by  fragments  of  corals  thrown  up  by  the  waves, 
till  it  becomes  so  high  as  to  be  covered  only  by  high  tides  and  at 
certain  seasons.     Masses  of  the  stone  thus  formed  are  sometimes 
separated  and  thrown  upon  the  surface  of  the  reef,  so  as  gradually 
to  augment  its  elevation.     The  calcareous  sand  on  the  top  now 
furnishes  a  soil  in  which  seeds  of  trees  and  plants  brought  by  the 

* 

What  is  the  nature  of  coral  reefs? 

What  conjectures  have  been  formed  respecting  their  extent  ? 
What  facts  have  been  ascertained  in  regard  to  the  different  classes  of 
animals  which  build  the  coral  islands  ? 

How  high  are  they  capable  of  rearing  their  structures? 

*  "Of  the  numerous  species  of  zoophytes  which  are  engaged  in  the  pro- 
duction of  coral  banks,  some  of  the  most  common  belong  to  the  genera 
Mt-andrina.,  Con/ophillia,  and  Astrea,  but  especially  the  latter." — LyelVs 
Prin.  of  Geol,  vol.  iii.  p.  221. 

t  "The  reefs  in  the  Pacific  are  sometimes  of  great  extent:  thus  the  in- 
habitants of  Disappointment  Islands,  and  those  of  Duff's  Group,  pay  visits 
to  each  other  by  passing  over  long  lines  of  reefs  from  island  to  island,  a 
distance  of  six  hundred  miles  and  upwards.  When  on  their  route  they 
present  the  appearance  of  troops  marching  upon  the  surface  of  the  ocean." 
LyelVs  Prin.  of  Geol.,  vol.  iii.  p.  235 ;  from  Malte-Brun's  Geography. 


356  GEOLOGY. 

waves  vegetate  rapidly,  and  overshadow  its  dazzling  white  sur- 
face. "  Entire  trunks  of  trees,  which  are  carried  by  the  rivers 
from  other  countries  and  islands,  find  here  at  length  a  resting- 
place  after  their  long  wanderings :  with  these  come  some  small 
animals,  such  as  lizards  and  insects,  as  the  first  inhabitants.  Even 
before  the  trees  form  a  wood,  the  sea-birds  nestle  here ;  strayed 
land-birds  take  refuge  in  the  bushes  :  and  at  a  much  later  period, 
when  the  work  has  been  long  since  completed,  man  appears,  and 
builds  his  hut  on  the  fruitful  soil."* 

169.  MM.  Quoy  and  Gaimard,  who  sailed  in  the  French  ex- 
pedition, more  recently,  under  Captain  Freycinet  also  examined 
with  attention  the  coral  rocks  and  islands  ;  and  they  were  led  to 
conclude  that  the  polypi  ferous  zoophytes  do  not  begin  building 
from  any  considerable  depths  below  the  surface  of  the  sea,  but 
merely  produce  incrustations  a  few  fathoms  in  thickness  ;    and 
that  the  appearance  of  these  reefs  and  islands  depends  on  the 
inequalities  of  the  mineral   masses  beneath,  the  circular  form  of 
many  of  them  indicating  their  foundation  on  the  crests  of  sub-? 
marine  craters.  It  is  supposed  that  those  species  of  animals,  which 
chiefly  contribute  to  the  formation  of  coralline  islands,  do  not  live 
in  water  at  the  depth  of  more  than  30  feet;  though  the  branched 
corals  have  been  brought  up  in  sounding  off  Cape  Horn,  in  about 
50  fathoms  water,  and  Reteporse  have  been  found  as  low  as  100 
fathoms;  but  these  do  not  form  solid  masses,  though  the  ruins  of 
their  habitations  might  in  time  compose  banks  that  would  serve  as 
platforms,  which  the  other  species  might  make  the  foundations  of 
their  more  compact  structures. 

170.  Observations  were  made,  during  a  recent  voyage  of  Captain 
Beechey  to  the  Pacific,  whence  it  may  be  inferred  that  the  eleva- 
tion of  coral  rocks  proceeds  in  general  very  slowly  ;  but  a  curious 
circumstance  noticed  by  Mr.  Lloyd,  while  engaged  in  his  survey 
of  the  isthmus  of  Panama,  shows  that  bodies  cast  on  submarine 
banks,  where  the  coral  animals  are  at  work,  may  be  very  speed- 
ily cemented    to   the   surface,  and  a   considerable   increase   of 
height  may  hence  take  place  in  a  short  time.     This  gentleman, 
"  seeing  some  beautiful  polypifers  on  the  coast,  detached  speci- 
mens of  them ;  and  it  being  inconvenient  to  take  them  away  at 
the  time,  he  placed  them  on  some  rocks  or  other  corals,  in  a  shel- 
tered and    shallow  pool  of  water.     Returning  to  remove  them 
a  few  days  afterwards,  it  was  found  that  they  had  secreted  stony 
matter,  and  fixed  themselves  firmly  to  the  bottom.     Now  this 
property  must  greatly  assist  in  the  formation  of  solid  coral  banks  ; 

What  is  the  progress  of  change  from  a  coral  reef  to  an  inhabitable 
island  ? 

At  what  depths  and  on  what  foundation  has  it  been  supposed  that  ihe 
coral  animals  commence  their  operations  ? 

What  peculiar  power  have  those  animals  in  regard  to  the  connexion  of 
their  structures  with  other  solid  substances  ? 

*  Lyell's  Prin.  of  Geol.  vol.  iii.  pp.  221,  222;  from  Kotzebue's  Voyage 
in  1815—1818,  vol.  iii. 


- 

EARTHQUAKES  AND  VOLCANOS.  357 

for  if  pieces  of  live  corals  be  struck  off  by  the  breakers,  and 
thrown  over  into  calm  water  or  holes,  they  would  affix  themselves 
and  add  to  the  solidity  of  the  mass."* 

171.  It  has  been  the  subject  of  curious  speculation  whence  the 
coral  polypifers  and  testaceous  mollusca  can  obtain  the  vast  quan- 
tities of  carbonate  of  lime,  which  they  secrete  to  form  the  enve- 
lopes by  which  they  are  protected.     Mr.  Bakewell  considers  it  as 
more  than  probable  that  they  have  the  extraordinary  faculty  of  pro- 
ducing- lime  from  simple  elements  ;f  and  Dr.  Macculloch  seems 
disposed  to  impute  its  origin,  in  the  same  manner,  to  the  influence 
of  vital  energy,  in  combining  elementary  bodies. £     If  this  were 
admitted,  it  would  follow  that  the  quantity  of  lime  on  the  surface 
of  the  earth  must  be  progressively  increasing,  unless  it  be  sup- 
posed that  other  natural  processes  are  regularly  taking  place  for 
the  decomposition  of  calcareous  earth,  or  rather  of  its  metallic 
basis,  calcium. 

172.  Mr.  Lyell,  in  opposition   to   this  doctrine,  says:  "We 
see  no  reason  for  supposing  that  the  lime  now  on  the  surface,  or 
in  the  crust  of  the  earth,  may  not,  as  well  as  the  silex,  alumine, 
or  any  other  mineral  substance,  have  existed  before  the  first  orga- 
nic beings  were  created,  if  it  be  assumed  that  the  arrangement  of 
the  inorganic  materials  of  our  planet  preceded  in  the  order  of  time 
the  introduction  of  the  first  organic  inhabitants. "§     He  adds,  in 
reference   to   the  abundance  of  carbonate  of  lime  furnished  by 
springs  which  rise  through  granite  : 

173.  "  But  if  the  carbonate  of  lime  secreted  by  the  testacea  and 
corals  of  the  pacific,  be  chiefly  derived  from  below,  and  if  it  be  a 
very  general  effect  of  the  action  of  subterranean  heat  to  subtract 
calcareous  matter  from  the  inferior  rocks,  and  to  cause  it  to  ascend 
to  the  surface,  no  argument  can  be  derived  in  favour  of  the  pro- 
gressive increase  of  limestone  from  the  magnitude  of  coral  reefs, 
or  the  greater  proportion  of  calcareous  strata  in  the  more  modern 
formations.     A  constant  transfer  of  carbonate  of  lime  from  the  in- 
ferior parts  of  the  earth's  crust  to  its  surface,  would  cause  through- 
out all  future  time,  and  for  an  indefinite  succession  of  geological 
epochs,  a  preponderance  of  calcareous  matter  in  the  newer,  as 
contrasted  with  the  older  formations."|j 

Earthquakes  and  Volcanos. 

174.  There  are  many  circumstances  which  indicate  such  a  con- 
nexion between  earthquakes  and  volcanos,  as  may  warrant  the 

What  different  conjectures  have  been  stated  in  regard  to  tbe  source  of 
the  materials  of  which  corals  are  composed  ?  How  may  the  abundance  of 
iime  on  or  near  the  surface  of  the  earth  be  explained  ? 

*  De  la  Beche's  Geol.  Man.,  p.  165. 

t  See  Introduction  to  Geology,  Silliman's  ed.  p.  86. 

\  System  of  Geology,  vol.  i.  p.  219. 

$  Principles  of  Geology,  vol.  iii.  pp.  241,  242. 

||  Principles  of  Geology,  u.  a, 


358  GEOLOGY. 

conclusion  that  they  depend  on  the  same  general  cause.  Both  these 
phenomena  are  manifestly  owing  to  the  agency  of  subterranean 
heat.  Volcanic  eruptions  of  lava  in  a  state  of  igneous  fusion,  of 
red-hot  stones  and  ashes,  and  of  columns  of  steam,  afford  suffi- 
cient evidence  of  the  very  high  temperature  that  must  subsist  in 
the  interior  of  the  earth.  The  phenomena  of  earthquakes,  also, 
which  seem  to  be  owing  to  the  sudden  expansion  of  gases,  va- 
pours, and  perhaps  of  solid  matter,  display  equally  characteristic 
effects  of  the  influence  of  internal  heat. 

175.  Earthquakes  and  volcanos  frequently  happen  at  the  same 
time ;  and,  indeed,  an  eruption  of  lava  from  a  burning  mountain, 
even  when  comparatively  inconsiderable,  can  hardly  take  place 
without  some  agitation  of  the  surface  of  the  surrounding  country  ; 
every  volcanic  paroxysm,  therefore,  is  probably  attended  with  an 
earthquake,  and  the  extent  of  the  commotion  is  usually  propor- 
tioned to  the  violence  of  volcanic  action.     Those  countries  in 
which  there  are  volcanos  are  more  frequently  visited  by  earth- 
quakes than  such  as  are  distant  from  them.     But  the  latter  are  by 
no  means  exempt  from  such  visitations.     Indeed,  there  is  perhaps 
no  part  of  the  earth's  surface  that  may  not  be  occasionally  shaken, 
though  there  are  many  in  which  the  experience  of  ages  has  led 
the  inhabitants  to  regard  such  phenomena,  so  far  as  relates  to 
themselves,  rather  as  objects  of  curiosity  than  of  alarm. 

176.  Next  to  those  countries  which  are  the  seats  of  open  or 
extinct  volcanos,  mountainous  districts,  and  especially  those  con- 
sisting of  primary  rocks,  are  the  most  frequent  scenes  of  earth- 
quakes ;  though  secondary  and  tertiary  hills,  wide  level  tracts, 
marshes  but  little  above  the  sea,  sandy  deserts  and  fertile  fields 
are  more  or  less  exposed  to  their  destructive  operation.     They 
occur  in  all  climates,  cold,  temperate,  or  tropical ;  as  is  also  the 
case  with  volcanos.    Both  kinds  of  phenomena  appear  to  be  more 
prevalent  near  the  sea-coast  than   elsewhere ;    thus    Syria,  the 
coasts  and  islands  of  Asia,  America,  the  countries  bordering  on 
the  Mediterranean,  and  Iceland,  have  been  repeatedly  devastated 
by  them;  while  the  plains  of  Asia,  Africa,  and  the  north  of  Eu- 
rope, experience  comparative  security. 

177.  The  occurrence  of  earthquakes  is  by  no  means  unfrequent. 
Mr.  Lyell  observes,  that  Von  Hoff  has  published  from  time  to  time, 
in  a  German  journal,  lists  of  the  earthquakes  which  have  happened 
since  1821 ;  and  from  these  it  appears  that  every  month  has  been 
signalized  by  one  or  more  convulsions  in  some  part  of  the  globe.* 

To  what  cause  are  earthquakes  and  volcanos  to  be  referred? 

What  pr"oof  have  we  of  the  justness  of  that  supposition? 

In  what  parts  of  the  globe  are  earthquakes  most  frequently  felt  ? 

What,  besides  volcanic  countries,  are  frequently  visited  by  earthquakes  1 

What  relation  appears  to  exist  between  inland  and  maritime  districts  in 
respect  to  the  frequency  of  their  occurrence  ? 

What  does  observation  prove  in  regard  to  the  periods  at  which  earth- 
quakes take  place  ? 

*  Principles  of  Geology,  vol.  ii.  p.  175. 


PHENOMENA  OF  EARTHQUAKES.  359 

The  recurrence  of  earthquakes,  either  where  they  are  common,  or 
where  they  are  slight  and  unfrequent,  has  not  been  observed  to 
take  place  at  any  particular  periods,  nor  to  be  influenced  by  the 
seasons  of  the  year,  and  they  happen  sometimes  by  day  and 
sometimes  at  night,  and  in  various  states  of  the  atmosphere.* 

178.  The  principal  phenomena  of  earthquakes  consists  of  trem- 
blings and  vibrations  of  the  surface  of  the  earth,  extending  to 
various  distances,  and  often  having  a  certain  direction.     These 
shocks  begin  in  general  with  elevations  of  the  ground,  followed 
by  horizontal  undulations,  and  in  some  instances  by  violent  irre- 
gular agitations,  and  by  vortical  or  gyratory  motions.     To  these 
may  be  added,  the  rending,  slipping,  rising,  and  sinking  of  the 
Boil  and  substrata ;  the  sudden  retreat  of  trie  sea,  and  its  impe- 
tuous return,  alternately  laying  bare  the  sands  and  beaches,  and 
in  its  tremendous  inroads  on  the  shores  sweeping  away  trees, 
buildings,  and  other  solid  masses ;  the  violent  agitation  of  lakes, 
which  sometimes  sink  into  the  earth;  the  drying  up  or  bursting 
forth  of  springs  and  rivers ;  and  the  occurrence  of  inundations, 
from  the  fall  of  fragments  of  rock  or  soil,  which  may  block  up 
their  channels. 

179.  The  distances  to  which  the  effects  of  earthquakes  extend 
are  very  great.     Thus  when  the  terrible  catastrophe  of  Lisbon 
happened  in   1755,  the  shock  was  felt  not  only  over  nearly  the 
whole  of  Europe,  but  also  in  the  West  Indies.     The  earthquake 
which  visited  the  coast  of  Chili,  November  19th,  1822,  is  said 
to  have  been   felt  simultaneously  throughout  a  space  of  1200 
miles  from  north  to  south.     And  in  the  same  year  Aleppo,  in 
Syria,  was  destroyed  by  an  earthquake,  the  influence  of  which 
extended  from  the  banks  of  the  Euphrates  to  the  island  of  Cy- 
prus, in  the  vicinity  of  which  two  rocks  are  stated  to  have  risen 
from  the  sea. 

180.  The  duration  of  shocks  has  been  variously  estimated,  from 
a  few  seconds  to  more  than  two  minutes.    It  is  probable,  however, 

What  influence  has  season,  weather  or  time  of  day  upon  their  recurrence  ? 
What  are  the  kinds  of  motion  felt  during  earthquakes? 
How  extensive  are  their  effects  when  most  violent  ? 

*  "  It  has  been  considered  that  earthquakes  are  presaged  by  certain 
atmospheric  appearances;  but  it  may  be  questionable  to  what  extent  this 
supposition  is  correct.  Historians  of  earthquakes  seem  to  have  been 
generally  desirous  of  producing  effect  in  their  descriptions,  adding  all  that 
CQuld  tend  to  heighten  the  horror  of  the  picture.  They  have  not  always, 
moreover,  been  anxious  or  able  to  separate  accidental  from  essential  circum- 
stances. As  far  as  my  own  experience  goes,  which  is,  however,  limited  to 
four  earthquakes,  the  atmosphere  seemed  little  affected  by  the  movement 
of  the  earth,  though  I  should  be  far  from  denying  that  it  may  be  so,  for 
we  can  scarcely  imagine  such  movements  to  arise  in  the  earth  without 
some  modification  or  change  of  its  usual  state  of  electricity,  which  would 
affect  the  atmosphere.  If  animals  be  generally  sensible  of  an  approaching 
shock,  (as  has  been  asserted,)  it  might  arise  as  well  from  electrical  changes, 
as  from  the  sounds  which  they  may  be  supposed  capable  of  distinguish- 
ing."—De  to  Beches  Geol.  Man.,  pp.  140,  141. 


360  GEOLOGY. 

that  single  agitations  seldom  last  more  than  half  a  minute,  and  are 
often  of  shorter  duration  ;  as  may  be  concluded  from  the  remarks 
of  observers  on  those  slighter  shocks  which  occur  in  situations 
where  the  apprehension  of  danger  is  not  likely  to  distract  the 
attention.  Though  the  shocks  are  sometimes  single,  yet  it  more 
frequently  happens  that  they  recur  rapidly  at  various  intervals ; 
and  in  volcanic  districts  especially,  they  have  been  repeated  oc- 
casionally for  months  or  years.  The  famous  earthquake  that 
desolated  Calabria,  in  Italy,  and  extended  across  the  strait  to 
Messina,  commenced  in  February,  1783,  and  the  shocks  continued 
till  the  close  of  1786. 

181.  Among  the  phenomena  caused  by  shocks,  there  are  few 
more  singular  than  those  which  result  from  the  gyrations  or  rota- 
tory movements,  which  have  been  already  noticed.     During  the 
earthquake  of  Catania,  the  general  direction  of  which  was  from 
south-east  to  north-west,  many  statues  were  turned  round  on  their 
pedestals,  and  a  large  mass  of  rock  was  turned  25°  from  the  south 
towards  the  east.    The  same  effect  was  more  remarkably  observa- 
ble during  the   earthquake  at  Valparaiso,Nin  November,  1822, 
when  many  houses  are  reported  to  have  been  turned  round,  and 
three  palm  trees  were  found  twisted  together  like  the  strands  of  a 
rope.     Earthquakes  are  almost  always  preceded  by  unusual  agi- 
tations of  the  waters  of  the  sea  and  of  lakes  ;  and  springs  some- 
times send  forth  torrents  of  fetid,  dark  mud.  A  noise  immediately 
precedes  the  shock,  which  has  been  described  as  resembling  the 
dragging  of  loaded  waggons  rapidly  over  a  rough  pavement,  an 
irregular  but   sudden  discharge  of  batteries  of  cannon,  or  the 
rushing  of  a  hurricane. 

182.  The  phenomena  of  slight  shocks  are  probably  in  general 
very  similar  to  those  which  were  noticed  in  England  in  1797.    A 
person  who  was  in  bed  at  Gloucester,  about  midnight,  and  hap- 
pened to  be  awake,  observed  an  undulation  of  the  surface  of  the 
ground,  extending  from  south-west  nearly  to  north-east,  and  the 
bedstead,  which  was  placed  in  that  direction,  seemed  to  be  slightly 
raised  from  foot  to  head,  and  sink  again  with  a  wave-like  motion  ; 
while  the  agitation  was  sufficient  to  cause  the  sashes  of  the  win- 
dows to  rattle,  much  in  the  same  manner  as  they  do  in  conse- 
quence  of  the  passing  of  carriages   through   streets  where  the 
excavations  for  vaults  and  sewers  extend  beneath  the  surface  ;  and 
it  was  reported,  that  in  some  houses  in  Gloucester,  plates,  dishes, 
and  other  articles  were  thrown  dowrn  from  the  shelves  on  which 
they  had  stood.     The  whole  lasted  not  more  than  a  few  seconds. 

183.  Before  we  proceed  to  consider  the  influence  of  earthquakes 
in  modifying  the  surface  of  the  earth,  and  the  different  opinions 

What  is  the  ordinary  duration  of  the  motion  produced  by  this  occur- 
rence ? 

What  singular  movement  in  bodies  produced  by  earthquakes  has  been 
observed  to  take  place  ? 

What  indications  of  approaching  earthquakes  are  afforded  by  the  ocean? 

What  kind  of  sounds  are  most  frequently  observed  to  attend  their  shock  ? 


VOLCANOS.  361 

that  have  been  advanced  as  to  the  extent  and  importance  of  their 
effects,  it  will  be  requisite  to  take  some  notice  of  volcanos,  with 
which  they  are  so  intimately  connected.  The  general  description 
of  volcanos  is  that  of  openings  in  the  crust  of  the  earth,  through 
which  are  ejected,  from  time  to  time,  various  gases,  cinders,  ashes, 
stones,  and  streams  of  lava,  composed  of  red-hot  melted  rocks. 
From  the  accumulation  of  matters  thus  discharged,  conical  emi- 
nences are  formed,  with  funnel-shaped  cavities  called  craters  ;  and 
they  generally  occupy  the  summits  of  isolated  peaks  or  mountains. 

184.  Volcanos  occur  in  all  quarters  of  the  globe,  and  are  often 
distributed  in  groups  over  wide  areas ;  as  in  the  volcanic  band 
which  includes  Sumatra,  Java,  the  Moluccas,  and  the  Philippine 
islands;  and  the  line  of  the  Andes  in  America,  extending  from 
Chili,  or  perhaps  from  Terra  del  Fuego,  to  Mexico.     They  are 
often  found  near  the  shores  of  continents,  or  in  islands  ;  and  hence 
it  has  been  supposed  that  they  have  some  necessary  connexion 
with  the  sea.     But  recent  researches  have  shown,  that  they  also 
occur,  though  more  rarely,  at  great  distances  from  the  ocean,  or 
any  considerable  body  of  salt  water. 

185.  Volcanic  mountains  differ  greatly  in  height.   That  of  Esk 
mount,  in  Jan  Mayen's  island,  between  70°  49'  north  latitude  and 
71°  8',  is  but  1500  feet  above  the  sea-beach,  in  Jameson's  bay; 
Vesuvius  is  3932  feet  above  the  level  of  the  sea;  Hecla,  in  Ice- 
land, rises  to  the  height  of  5000  feet;  and  that  of  Etna,  in  Sicily, 
is  10,870  feet :  but  the  loftiest  mountains  are  those  of  the  Andes ; 
as  Pichincha,  the  height  of  which  is  about  15,931  feet;    Coto- 
paxi  has  an  elevation  of  18,8G7  feet,  and  Antisana  attains  that  of 
19,136  feet.    Volcanos  occur  in  various  latitudes,  from  Greenland 
and  Kamtschatka  to  Sumatra  and  Columbia;  nor  is  the  sea  by 
any  means  exempt  from  them,  numerous  islands  having  at  diifof- 
ent  periods  been  raised  by  volcanic  action  from  the  bed  of  the 
ocean  in  different  parts  of  the  world,  some  of  which  have  remained 
permanently  above  the  waves,  though  most  of  those  whose  origin 
has  been  noticed  have  subsequently  sunk,  forming  only  submarine 
reefs  and  sandbanks.* 

186.  The  number  of  the  volcanos  now  occasionally  in  activity 
has  been  stated  by  some  to  be  about  two  hundred ;  though,  accord- 
ing to  others,  they  amount  to  rather  more  than  three  hundred,  in- 
cluding solfataras,  or  smoking  volcanos.    But  besides  those  from, 
which  eruptions  have  issued  within  the  period  to  which  our  records 
extend,  there  are  many  extinct  volcanos,  of  which  abundant  traces 
remain  in  several  countries.     Thus  in  France,  the  territories  of 

What  is  meant  by  the  term  volcano  ? 

How  are  volcanos  distributed  over  the  surface  of  the  earth? 

At  what  different  elevations  do  they  occur? 

What  number  of  active  \olcanos  has  been  ascertained  to  exist? 

*  For  an  interesting  account  of  a  volcano  in  the  island  of  Hawaii,  (or 
Owhyhee,)  the  reader  is  referred  to  Silliman's  Am.  Journal  of  Science  vol 
xx.,  p.  228;  and  vol.  xxv.,  p.  199. — ED. 
2H 


362  GEOLOGY. 

Auvergne,  Vivarais,  and  the  Cevennes,  exhibit  conical  mountains, 
composed  of  lava,  scoria?,  and  volcanic  ashes ;  and  in  some  of 
them  the  forms  of  the  craters  may  still  be  discovered.  The  dis- 
trict around  the  town  of  Olot,  in  Catalonia,  and  that  of  the  Eifel 
and  the  Lower  Rhine,  in  Germany,  present  similar  appearances. 

187.  Some  volcanos  are  perpetually  active,  as  is  the  case  with 
that  of  Stromboli,  in  the  Mediterranean.  It  is  mentioned  by  Pliny ; 
and  there  is  reason  to  believe  that  its  eruptions  have  been  almost 
incessant  during  the  last  two  thousand  years.  According-  to 
Dolomieu,  its  crater  does  not  exceed  fifty  paces  in  diameter.  "I 
saw  it  dart,"  says  that  writer,  "  during  the  night,  at  regular  intejr- 
vals  of  seven  or  eight  minutes,  ignited  stones,  which  rose  to  the 
height  of  more  than  100  feet,  forming  radii  a  little  diverging  ;  but 
of  which  the  greater  number  fell  into  the  crater,  while  others  roll- 
ed even  to  the  sea.  Each  explosion  was  accompanied  with  a  burst 
of  red  flame."  Mr.  G.  P.  Scrope,  from  personal  observation  on 
this  volcano,  states,  that  "  there  evidently  exists  within  and  below 
the  cone  of  Stromboli,  amass  of  lava,  of  unknown  dimensions,  per- 
manently liquid,  at  an  intense  temperature,  and  continually  tra- 
versed by  successive  volumes  of  aerifom  fluids,  which  escape  from 
its  surface — thus  presenting  exactly  all  the  characters  of  a  liquid 
in  constant  ebullition."* 

188.  Among  those  which  may  be  styled  intermitting  volcanos, 
the  most  important  are  found  amidst  the  Andes.  Cotopaxi  is  the 
loftiest  of  these  burning  mountains,  from  which,  at  recent  epochs, 
eruptions  have  proceeded.  It  is  also  the  most  dreadful  of  all  those 
in  Quito,  and  subject  to  the  most  frequent  destructive  explosions. 
The  mass  of  scoriae,  and  the  huge  fragments  of  rocks  thrown  out  of 
this  volcano,  cover  a  surface  of  several  square  leagues,  and  would 
form,  were  they  heaped  together,  a  colossal  mountain.  In  1758, 
the  flames  rose  2900  feet  above  the  brink  of  the  crater.  In  1744, 
the  roaring  of  the  volcano  was  heard  on  the  borders  of  the  Magda- 
lena,  a  distance  of  about  200  leagues.  On  the  4th  of  April,  1768, 
the  quantity  of  ashes  ejected  by  the  volcano  was  so  great  that  the 
inhabitants  of  the  towns  of  Hambato  and  Tacunga,  were  obliged 
to  use  lanterns  to  walk  the  streets  at  noon  day.  The  explosion, 
which  took  place  in  January,  1803,  was  preceded  by  the  sudden 
melting  of  the  snows  that  covered  the  mountain.  For  twenty  years 
before,  no  smoke  or  vapour  had  been  observed  to  issue  from  the 
crater ;  and  in  a  single  night,  the  subterraneous  fire  became  so 
active  that  at  sunrise  the  external  walls  of  the  cone  were  heated 

Where  have  extinct  volcanos  been  observed  ? 

What  distinction  has  been  founded  on  the  periods  of  activity  in  vol- 
canos ? 

What  example  of  constantly  acting  volcanos  can  be  given  ? 

Where  are  the  most  important  intermitting  volcanos  found  ? 

What  remarkable  events  have  been  observed  in  the  eruptions  of  Coto- 
paxi? 

*  Considerations  on  Volcanos,  by  G.  P.  Scrope,  F.  R.  S. 


ERUPTION  OF  TOMBORO.  363 

to  such  a  temperature  as  to  appear  quite  naked,  and  of  the  dark 
colour  characteristic  of  vitrified  scoriae.* 

189.  One  of  the  most  dreadful  volcanic  er-uptions  on  record,  is 
that  which  occured  in  the  mountain  of  Tomboro,  in  the  island  of 
Sumbawa,  eastward  of  Java,  in  April,  1815.   It  commenced  on  the 
5th  of  April,  was  most  violent  on  the  llth  and  12th,  and  did  not 
cease  entirely  till  July.     Out  of  a  population  of  twelve  thousand 
persons  only  twenty-six  escaped  destruction.  Violent  whirlwinds 
swept  away  men,  horses,  cattle,  and  every  thing  which   came 
within  their  vortex,  tore  up  the  largest  trees,  and  covered  the  neigh- 
bouring sea  with  floating  timber,  f  Large  tracts  of  land  were  inun- 
dated by  lava,  several  streams  of  which  issuing  from  the  crater, 
reached  to  the  sea.  Vast  clouds  of  volcanic  dust  and  ashes,  as  be- 
fore mentioned,  were  conveyed  to  immense  distances,  blackening 
the  air,  and  for  a  time  eclipsing  the  sun.  The  floating  cinders  to 
the  westward  of  Sumatra,  formed  on  the  12th  of  April  a  mass  two 
feet  in  depth,  and  several  miles  in  surface,  through  which  ships 
with  difficulty  forced  their  way. 

190.  A  captain  of  a  ship,  who  was  at  Macassar  on  the  llth  of 
April,  says  :  "  By  noon,  the  light  that  had  remained  in  the  eastern 
part  of  the  horizon  disappeared,  and  complete  darkness  had  cover- 
ed the  face  of  day:  our  decks  were  soon  covered  with  falling  mat- 
ter ;  the  awnings  were  spread,  fore  and  aft,  to  prevent  it  as  much 
as  possible  from  getting  below ;  but  it  was  so  light  and  subtile, 
that  it  pervaded  every  part  of  the  ship.  The  darkness  was  so  pro- 
found through  the  remainder  of  the  day,  that  I  never  saw  any  thing 
equal  to  it  in  the  darkest  night ;  it  was  impossible  to  see  your  hand 
when  held  up  close  to  the  eye.    The  ashes  continued  to  fall  with- 
out intermission  through  the  night.  At  six  o'clock  the  next  morn- 
ing, when  the  sun  ought  to  have  been  seen,  it  still  continued  as 
dark  as  ever ;  but  at  half  past-seven  I  had  the  satisfation  to  per- 
ceive that  the  darkness  evidently  decreased,  and  by  eight  I  could 
faintly  discern  objects  on  the  deck.  From  this  time  it  began  to  get 
lighter  very  fast,  and  by  half-past  nine  the  shore  was  distinguish- 
able;  the  ashes  falling  in  considerable  quantities,  though  not  so 
heavily  as  before." 

191.  "  The  appearance  of  the  ship,  when  daylight  returned,  was 
most   extraordinary ;   the  masts,  rigging,  deck,  and  every  part 
being  covered  with  the  falling  matter ;  it  had  the  appearance  of 
calcined  pumicestone,  nearly  the  colour  of  wood  ashes ;  it  lay  in 

What  meteorological  occurrences  attended  the  eruption  of  Tomboro  ? 
What  account  has  been  given  of  the  extent  and  depth  of  the  darkness 
produced  by  the  floating  cinders  ? 

*  Edinburgh  Review,  vol.  xxiv.  p.  142 ;  from  Humboldt's  Researches 
concerning  America. 

t  For  a  theory  of  tornados,  referring  them  to  a  disturbance  of  atmospheric 
equilibrium  by  the  condensation  of  vapour  and  the  consequent  heating 
of  superior  strata  of  air,  causing  strong  ascending  currents,  see  the  subse- 
quent treatise  on  meteorology, — ED. 


364  GEOLOGY. 

heaps  of  a  foot  in  depth  in  many  parts  of  the  deck,  and  I  am  con- 
vinced several  tons  weight  were  thrown  overboard  ;  for  although 
a  "perfectly  impalpable  powder  or  dust  when  it  fell,  it  was,  when 
compressed,  of  considerable  weight.  A  pint  measure  filled  with 
it  weighed  12|  ounces ;  it  was  perfectly  tasteless,  and  did  not  effect 
the  eyes  with  any  painful  sensation  ;  it  had  a  faint,  burning  smell, 
but  nothing  like  sulphur.  By  noon,  on  the  12th,  the  sun  again 
appeared,  but  very  faintly,  through  the  dusky  atmosphere,  the  air 
still  being  charged  with  the  ashes,  which  continued  to  fall  lightly 
all  that  day  and  the  succeeding  one." 

19*2.  Along  the  sea-coast  of  Sumbawa,  and  the  neighbouring 
islands,  the  water  rose  suddenly  from  two  to  twelve  feet,  great 
waves  rushing  up  the  estuaries,  and  again  retreating.  At  Bima, 
about  40  miles  westward  of  the  volcano,  though  the  wind  was  still 
during  the  whole  time  of  the  eruption,  the  sea  rolled  in  upon  the 
shore  and  filled  the  lower  parts  of  the  houses  with  water  a  foot  deep. 
Every  prow  and  boat  was  driven  from  its  anchorage,  and  thrown 
ashore.  The  perpendicular  depth  of  the  ashes  that  fell  here  was 
found  to  be  3|  inches.  The  noise  of  the  explosions,  as  heard  from 
this  place  on  the  14th,  is  said  to  have  been  most  terrific,  resem- 
bling the  reports  of  a  heavy  mortar  fired  close  to  the  ear.  The 
town  called  Tomboro,  on  the  western  side  of  the  volcano,  was 
overflowed  by  the  sea,  which  encroached  upon  the  shore  at  the 
foot  of  the  mountain,  so  as  to  leave  the  land  permanently  sub- 
merged to  the  depth  of  18  feet.* 

193.  "The  changes  produced  by  such  eruptions  as  that  here 
recorded,  would,  independently  of  the  alteration  in  the  shape  of 
the  volcano  itself,  and  of  the  streams  of  lava  which  flowed  from 
it,  extend  to  very  considerable  distances.  On  the  dry  land,  vege- 
tables and  animals  would  be  entombed  beneath  stones  and  ashes, 
the,  quantity  of  the  covering  matter  probably  increasing  with  the 
proximity  of  the  volcano.  And  if  it  should  chance,  as  sometimes 
happens,  that  the  aqueous  vapours  discharged  from  the  volcanic 
vent  were  suddenly  condensed, f  the  torrents  produced  would 
sweep  away  not  only  the  looser  riarts  of  the  volcano,  but  also  the 
plants  and  animals  which  they  might  encounter,  imbedding  them 
in  a  thick  mass  of  alluvial  matter.  The  vegetable  and  animal 
substances  enveloped  by  the  discharged  ashes,  cinders,  and  stones, 
falling  into  the  sea,  would  be  both  marine  and  terrestrial ;  and  a 
very  curious  mixture,  so  far  as  regarded  its  organic  contents, 
would  be  observed :  trees,  men,  cattle,  fish,  corals,  and  a  great 

What  sensible  qualities  were  possessed  by  the  cinders  which  fell  on 
that  occasion? 

How  was  the  sea  affected,  and  what  evidence  have  we  that  it  arose  from 
other  than  the  ordinary  causes  ? 

What  important  geological  phenomena  may  result  from  such  occurrences 
as  at  Tomboro  ? 

*  Brande's  Journal  of  Science,  vol.  i.;  Hist,  of  Java,  by  Sir  T.  S.  Raffles 
vol.  i.  p.  28,  &c. ;  Life  of  Sir  T.  S.  Raffles, 
t  See  note  on  preceding  page. — ED. 


SUBMARINE  VOLCANOS.  365 

variety  of  marine  remains,  would  be  incased,  and  it  might  so 
happen  that,  both  on  the  land  and  in  the  sea,  a  bed  of  lava  might 
cover  such  accumulations."* 

194.  The  quantity  of  solid  matter  ejected  from  some  volcanos 
is  immensely  great.     Vesuvius,  Etna,  and  other  volcanic  moun- 
tains have,  at  different  times,  discharged  lava,  cinders,  and  ashes, 
the  total  bulk  of  which  would  at  least  equal  that  of  the  mountains 
whence  they  issued.     During  one  eruption  of  Etna,  an  area  150 
miles  in  circumference  is  said  to  have  been  covered  with  a  stratum 
of  volcanic  sand  or  ashes  12  feet  deep.   In  1775,  the  same  xolcano, 
according  to  Dolomieu,  poured  out  a  stream  of  lava  12  miles  in 
length,  1^  in  breadth,  and  200  feet  in  thickness.   That  writer  also 
states,  that  some  of  the  currents  of  lava  from  Etna  are  10  leagues 
in  length,  and  3  in  breadth. f    But  the  most  extensive  known  cur- 
rent of  modern  lava  appears  to  be  that  formed  by  a  volcano  in 
Iceland,  in  1783,  which  is  60  miles  long,  and  12  broad,  equalling 
in  extent  any  continuous  rock  formation  in  England.^:  The  surface 
of  the  country  for  many  leagues  round  Naples  seems  to  be  com- 
posed of  volcanic  matter.     Herculaneum  and  Pompeii,  which  were 
covered  by  vast  showers  of  ashes  during  the  first  recorded  eruption 
of  Vesuvius,  A.  D.  79,  when  they  were  partially  disinterred  in 
the  course  of  the  last   century,   were  ascertained  to  have  been 
founded  on  a  volcanic  rock,  and  their  streets  were  paved,  and 
some  of  their  buildings  constructed  of  blocks  of  lava,  of  uncertain 
but  early  origin. 

195.  The  present  cone  of  Vesuvius  is  supposed  to  have  been 
formed  since  the  eruption  just  mentioned,  and  the  more  ancient 
lavas  to  have  flowed   from   the  adjacent  mountain,  now  called 
Somma.     Near  Puzzuoli,  on  the  coast  of  the  bay  of  Baiae,   a 
mountain  was   thrown  up  suddenly,  September  29,  1538,  after 
repeated  shocks  of  earthquake.     Its  present  height  is  440  feet 
above  the  level  of  the  sea;  and  it  is  about  1£  miles  in  circum- 
ference.    This  volcanic  cone  is  called  monte  Nuovo ;  and  at  a 
short  distance  from  it  is  another  of  more  ancient  date,  and  larger 
dimensions,  named  monte  Barbaro. 

196.  The  phenomena  of  submarine  volcanos  resemble,  in  many 
respects,  those  of  sub-aerial  volcanos ;  the  chief  difference  consist- 
ing in  the  more  copious  emission  of  aqueous  vapour  and  gases, 
and  in  the  formation  of  temporary  or  permanent  islands.     It  is 
probable  that  Owhyhee,  and  many  other  islands  in  the  Pacific, 
were  formed  in  this  manner;    as  also  the  Canary  islands,  the 
Azores,  and  several  others.§  Such  likewise  was  the  origin  of  the 

What  striking  facts  illustrate  the  force  and  duration  of  volcanic  actions? 
What  evidence  have  we  that  Herculaneum  and  Pompeii  were  not  de- 
stroyed by  the  first  eruption  of  Vesuvius? 
What  extinct  volcanos  are  found  in  Italy  ? 

*  De  la  Beche's  Geol.  Man.  p.  132. 
t  Memoir  sur  les  Isles  Ponces,  &c.  p.  166. 
J  Bakewell's  Introd-  to  Geol.,  p.  378. 

$  See  the  reference  to  Am.  Journal  of  Science,  on  page  361. 
2H2 


366  GEOLOGY. 

Lipari  islands,  as  wo  learn  from  history;  and  of  some  of  those  in 
the  Grecian  archipelago,  where  a  new  island  arose  in  1707,  called 
Nea  [New]  Kaimeni,  near  Santorin,  which,  as  well  as  some  of 
those  adjacent,  was  thrown  up  at  a  more  remote  period.*  Among 
the  numerous  instances  on  record  of  islands  produced  by  subma- 
rine volcanos  which  have  subsequently  sunk  beneath  the  surface 
of  the  water,  one  of  the  most  recent  occurrence  was  that,  the 
elevation  of  which  took  place  in  July,  1831,  between  the  island 
of  Pantellaria  and  the  coast  of  Sicily.  This  has  been  circumstan- 
cially  described  by  different  observers  ;  but  for  the  highly  inter- 
esting details  we  must  refer  to  the  annexed  authorities.]" 

197.  Some  volcanos  eject  only  gases  and  vapours,  and  these 
are  called  solfataras,  or,  where  the  cones  are  very  small,  fumarole, 
and  in  Mexico,  hornitos  ;  others  send  forth  torrents  of  water  and 
mud,  as  is  the  case  with  the  volcano  of  Macalubba,  in  Sicily,  and 
frequently  with  the  volcanic  peaks  of  the  Andes  ;  but  the  more 
usual   products   of  volcanic   action   are   streams    of    lava,   and 
showers  of  scoriae,  sand,  and  ashes,  accompanied,  however,  by 
clouds  of  steam  and  gas.     As  to  the  composition  of  lavas,  exact 
information  is  wanting.  However,  Mr.  Phillips  says,  "  it  is  nearly 
certain  that  feldspar  and  augite  are  the  principal  ingredients,  and 

'that  the  colour  of  the  lava  is  dependent  on  the  prevalence  of  the 
one  or  the  other. 

198.  "The  minerals  which   are  discoverable  as  entering,  in 
notable  proportion,  into  the  composition  of  volcanic  masses,  are 
very  few  ;    as  feldspar,   compact  feldspar,    augite,   hornblende, 
oxidulous   iron,  olivine,  mica,  leucite  ;   other   minerals,  indeed, 
are  found  in  their  cavities,  but  these  can  scarcely  be  said  to  enter 
into  the  composition  of  the  rock." — "  It  is  remarkable,  that  quartz, 
so  extremely  abundant  in  rocks  of  which  the  composition  is  not 
suspected  to  be  of  volcanic  origin,  is  scarcely  ever  found  in  such 
as  are  decidedly  volcanic."^:   It  must,  however,  be  observed  that 
Mr.  Poulett  Scrope  enumerates   among  volcanic  rocks,  quartz- 
iferous  trachyte,  containing  numerous  crystals  of  quartz ;    and 
siliceous  trachyte,  having  much  silex  in  its  composition. § 

199.  As   to  the   causes  of  volcanos  and  earthquakes,  various 
opinions  have  been  proposed,  some  of  which  appear  to  be  quite 
inconsistent  with  the  effect  produced.    Thus  Werner  and  his  dis- 

In  what  particulars  do  submarine,  differ  from  other  volcanos  ? 

What  striking  examples  of  this  kind  of  volcanos  are  found  in  different 
parts  of  the  globe  ? 

To  what  is  the  term  solfatara  applied  ? 

What  mineral  ingredients  are  most  abundant  in  the  matter  ejected  from 
volcanos  ? 

*  Lyell's  Prin.  of  Geol.,  vol.  ii.  pp.  151—155. 

t  Philos.  Transactions  for  1833  ;  Journal  of  Geographical  Society,  1831 , 
Annales  des  Sciences  Naturelles,  torn.  xxiv. ;  and  Lyell's  Principles  of 
Geology,  vol.  ii.  pp.  145 — 150. 

t  Outlines  of  Mineralogy  and  Geology,  p.  264. 

$  Quarterly  Journal  of  Science,  vol.  xxi.  1826 


CAUSE  OF  EARTHQUAKES  AND  VOLCANOS.  367 

oiples  attributed  them  to  the  spontaneous  combustion  of  beds  of 
coal ;  and  others  imputed  their  origin  to  the  inflammation  of  vast 
repositories  of  sulphur  or  petroleum,  collected  in  caverns  of 
the  earth ;  and  the  experiment  of  Lemery,  noticed  elsewhere,* 
has  been  alleged  as  affording  an  explanation  of  the  manner  in 
which  sulphur  and  iron  might  take  fire  when  buried  in  the  earth. 
A  more  plausible  hypothesis  was  proposed  by  Sir  H.  Davy,  who 
having  discovered  that  potash  and  soda  were  the  oxides  of  highly 
inflammable  rnetals,  which  become  oxidated  wilh  the  extrication 
of  abundance  of  heat  when  they  come  in  contact  with  water, 
sought  to  explain  volcanic  phenomena,  by  imagining  the  existence 
of  large  quantities  of  the  metallic  bases  of  the  alkalis  within 
the  bowels  of  the  earth,  and  their  sudden  oxidation  through  the 
access  of  sea-water  to  the  cavities  in  which  they  were  contained. 
This  theory  has  been  adopted  and  advocated  recently  by  Dr.  Dau- 
beny,  in  his  "  Description  of  Active  and  Extinct  Volcanos  ;"  but  it 
seems  inadequate  to  the  full  development  of  the  agency  on  which 
the  vast  power  and  extensive  influence  of  these  phenomena  de- 
pends. ... 

200.  Earthquakes  and  volcanos  may  be  supposed  to  have   a 
common  origin,  since  volcanic  eruptions  are  generally  preceded 
by  agitations  of  the  surface  of  the  earth,  such  as  would  necessa- 
rily be  caused  by  the  efforts  of  heated  and  expanded  fluids,  either 
liquid  or  gaseous,  and  especially  of  the  latter,  embowelled  in  the 
earth,  to  escape  through  the  superincumbent  strata.     It  is  true, 
that  earthquakes  happen  frequently  in  countries  where  there  are 
now  no  volcanos,  and  it  may  be  admitted,  that  they  sometimes 
are  neither  accompanied  nor  followed  by  volcanic  eruptions  ;  but 
this  only  proves,  that  the  elastic  force  of  expansive  fluids  confined 
within  the  earth,  may  not  always  be  sufficiently  powerful  to  over- 
come  at  once  the  resistance  to   their  exit,  and   therefore   they 
cause  concussions  of  the  surface  ;  and  accordingly  it  has  been  ob- 
served, that   repeated  earthquakes  during  longer  or  shorter  pe- 
riods have  frequently  preceded  violent  volcanic  eruptions. 

201.  If,  then,  earthquakes  and  volcanos  depend  on  the  same 
causes,  the  source  of  these  phenomena  must  be  very  deeply  seated 
below  the  earth's  surface  :  f>r  though  volcanos  might  be  regard- 
ed as  confined    to   certain   localities,  the  action  of  earthquakes 
seems  to  be  almost  unlimited,  since  these  concussions  of  the  sur- 
face have  been  felt  over  nearly  half  the  globe.     Mr.  Bake  well,  in 
reference  to  the  earthquake  of  Lisbon,  the  shock  of  which  was 
perceived  in  the  United  States  and  the  West  Indies,  observes, 
that  "the  cause  which  could  effect  a  simultaneous  concussion 
over  such  a  vast  extent,  must  probably  have  been  seated  nearly 

What  different  theories  have  been  adopted  to  account  for  volcanic  phe- 
nomena ? 

What  circumstances  indicate  that  earthquakes  and  volcanos  proceed 
from  a  common  cause  ? 

*  See  Treatise  on  Chemistry. 


368  GEOLOGY. 

midway  between  the  centre  of  the  globe  and  its  surface."* 
Such  widely  acting  power  cannot  reasonably  be  ascribed  to  the 
topical  agency  of  chemical  affinities  ;  and  hence  some  bold  specu- 
lators have  inferred,  that  these  phenomena  are  connected  with  the 
central  fire,  or  rather  with  the  candescent  matter  supposed  to  exist 
in  the  interior  of  the  earth.  Volcanos,  therefore,  are  considered 
as  safety-valves,  by  means  of  which  some  portions  of  the  sub- 
stances in  fusion  which  form  the  internal  mass,  escape  from 
time  to  time,  with  violence,  to  flow  over  the  surface  of  the  soil.f 

202.  The  electric  influence,  whatever  may  be  its  nature,  cannot 
but  be  considered  as  one  of  the  most  powerfully  active  causes  of 
the  changes  which  have  at  former  periods  been  produced  in  the 
surface  of  the  earth  as  well  as  of  those  which  are  now  in  progress. 
But  notwithstanding  the  discoveries  which  have  been  recently 
made  relative  to  electricity,  and  its  connexion  with  magnetism, 
we  are  still  too  little  acquainted  with  its  mode  of  action  to  be 
enabled  fully  to  appreciate  the  extent  of  its  operations. 

203.  There  can  be  no  doubt  but  the  chemical  combinations  and 
decompositions  of  bodies  on  the  surface  of  the  earth  must  be  greatly 
influenced  by  atmospheric  electricity ;  and  there  is  some  reason 
for  concluding  that    subterranean   phenomena    may  depend    on 
its  mysterious  agency.     "  Now  the  identity  of  magnetism  and 
electricity  seems,  in  many  respects,  to  be  established,  it  may  de- 
serve consideration,  whether  an  interruption  to  the  magnetic  or 
electric  currents  which  circulate  through  the  earth,  may  not  some- 
times occasion  earthquakes  acting  almost  instantaneously  under 
large  portions  of  the  globe.     If,  as  some  philosophers  maintain, 
there  is  a  central  fire  under  every  part  of  the  globe,  or  if  certain 
spaces  only  are  filled  with  ignited  matter,  we  can  scarcely  doubt 
that  chemical  changes  are  taking  place,  which  will  also  change 
the  electrical  relations  between  the  mineral  beds.     A  series  of 
strata  may  act  like  the  plates  of  an  immense  Voltaic  battery,  and 
discharge  the  electricity  from  one  internal  part  of  the  globe  to 
another,  exciting  vibrations  that  may  agitate   a   whole   hemis- 
phere.":}: 

204.  Researches  concerning  the  extent  and  importance  of  the 
modifications  of  the  earth's  surface,  which  have  resulted  from  the 
action  of  existing  causes,  have  led  different  philosophers  to  dis- 
cordant conclusions  relative  to  the  nature  of  that  agency  which 

At  what  depth  beneath  the  surface  must  that  cause  be  seated  ? 

How  does  this  appear  ? 

In  what  light  are  volcanos  to  be  considered  in  reference  to  internal 
fires? 

Which  of  the  imponderable  agents,  besides  heat,  is  probably  concerned 
in  producing  the  changes  now  in  progress  on  the  globe  ? 

What  analogy  lias  been  supposed  to  exist  between  terrestrial  strata  and 
Voltaic  plates  ? 

*  Introduction  to  Geology,  p.  373. 

t  Bertrand  Lettres  sur  les  Rev.  du  Globe,  p.  69. 

J  Bakewell's  Introd.  to  Geology,  p.  375. 


GEOLOGICAL  SPECULATIONS.  369 

produced  the  rocks  composing  the  crust  of  the  earth,  and  occa- 
sioned the  dislocations  and  changes  they  have  undergone  at  far 
distant  and  unknown  periods.  While  some  assert  the  efficiency 
of  the  causes  now  in  action,  others  represent  them  as  inadequate 
and  insignificant.  With  regard  to  the  effects  of  winds,  currents, 
and  other  modifying  causes,  Mr.  Conybeare  has  the  following 
remarks: 

205.  "These  actions  appear  to  be  circumscribed  within  very 
narrow  limits :  over  a  great  part  of  the  earth's  surface  the  influence 
of  these  wasting  causes  is  absolutely  null,  the   mantle  of  green- 
sward that  invests  it  being  an  effectual  protection.     The  barrows 
of  the  aboriginal  Britons,  after  a  lapse  of  certainly  little  less,  and 
in  many  instances  probably  more,  than  two  decads  of  centuries, 
retain  very  generally  all  the  pristine  sharpness  of  their  outline ; 
nor  is   the  slight  fosse  that  sometimes  surrounds  them  in  any 
degree  filled  up 

206.  "  Causes,  then,  which   in  two  thousand  years  have  not 
affected  in  any  perceptible  manner  these  small  tumuli,  so  often 
scattered  in  very  exposed  situations  over  the  crests  of  our  hills, 
can  have  exerted  no  very  great  influence  on  the  mass  of  those  hills 
themselves  in  any   assignable  portion  of  time,  which  even  the 
imagination  of  a  theorist  can  allow  itself  to  conceive  ;  and  where 
circumstances  are  favourable  to  a  greater  degree  of  waste,  still 
there  is  often  a  tendency  to  approach  a  maximum  at  which  fur- 
ther waste  will  be  checked ;  the  abrupt  cliff  will  at  last  become  a 
slope,  and   that   slope  become  defended  by  its  grassy  coat  of 
proof. 

207.  "  It  should  appear,  that  even  the  action  of  the  sea,  certainly 
the  most  powerful  and  important  of  all  those  we  have  surveyed, 
has  a  similar   tendency  to  impose  a  limit   to  its  own  ravages. 
It  has  obviously  in  many  instances  formed  an  effectual  barrier 
against  itself,  by  throwing  up  shingle-banks  and  marsh-lands  in 
the  face  of  cliffs  against  which  it  once  beat ;  and  after  the  de- 
struction has  been  carried  to  a  certain  point,  it  appears  necessary 
from  the  mode  of  action,  (excepting  where  very  powerful  currents 
interfere,)  that  the  very  materials  resulting  from  the  ruin  should 
check   any  further  increase ;  even  where  these   currents   exist, 
these  also  have  a  tendency  to  throw  up  barriers  of  shingle  in  their 
eddy.     Historical  records,   and   the   very    nature   and   physical 
possibilities  of  the  case,  alike  compel  us  to  dissent  entirely  from 
those  crude  and  hasty  speculations,  which  would  assign  to  the 
causes  now  in  action,  the  power  of  producing  any  very  material 
change  in  the  face  of  things  ;"and  which  would  refer  to  these 
alone,  acting  under  their  present  conditions,  and  with  only  their 

What  effect  has  vegetation  on  the  rapidity  of  changes  on  the  earth's 
surface  ? 

How  is  this  exemplified  in  Great  Britain? 

What  limits  the  power  of  the  ocean  to  wear  away  its  shores  ? 


370  GEOLOGY. 

present  forces,  the  mighty  operations  which  have  formed  and  mo- 
dified our  continents."* 

208.  Mr.  Conybeare  does  not  here  distinctly  mention  earth- 
quakes and  volcanos  among  the  existing  causes  of  alteration  of 
the  surface  of  the  earth ;  and  as  he  could  not  have  overlooked 
their  influence,  it  is  probable  that  he  regarded  their   action   as 
being  too  limited  to  produce  any  considerable  effect.     Mr.  De  la 
Beche,  who  also  asserts  the  dissimilarity  of  the  ancient  and  mo- 
dern  modifying  causes  of  terrestrial   conformation,  makes  the 
following  observations  on  the  phenomena  to  which  we  have  just 
alluded : 

209.  *'  If  we  withdraw  ourselves  from  the  turmoil  of  volcanos 
and  earthquakes,  and  cease  to  measure  them  by  the  effects  which 
they  have  produced  upon  our  imaginations,  we  shall  find  that  the 
real  changes  they  cause  on  the  earth's  surface  are  comparatively 
small,  and  quite  irreconcilable  with  those  theories  which  propose 
to  account  for  the  elevations  of  vast  mountain  ranges,  and  for 
enormous  and  sudden  dislocations  of  strata,  by  repeated  earth- 
quakes acting  invariably  in  the  same  line,  thus  raising  the  moun- 
tains by  successive  starts  of  five  or  ten  feet  at  a  time,  or  by  catas- 
trophies  of  no  greater  importance  than  a  modern  earthquake.     It 
is  useless  to  appeal  to  time :  time  can  effect  no  more  than  its 
powers  are  capable  of  performing:  if  a  mouse  be  harnessed  to  a 
large  piece  of  ordnance,  it  will  never  move  it,  even  if  centuries 
on  centuries  could  be  allowed  ;  but  attach  the  necessary  force, 
and  the  resistance  is  overcome  in  a  minute."f 

210.  Among  those  writers  who  have  taken  the  opposite  side  of 
the  question,  and  maintained  the  efficacy  of  causes  now  operating 
to  have  produced  the  more  ancient  modifications  of  the  surface  of 
the  earth,  Mr.  Lyell  has  distinguished  himself  by  the  learning  and 
ability  displayed  in   support  of  the   opinions   he  has   adopted. 
The  full  force  of  his  arguments  can  only  be  appreciated  by  those 
who  have  the  opportunity  for  examining  the  extensive  mass  of 
information  which  he  has  collected  in  his  treatise  on  "  The  Prin- 
ciples of  Geology."j~     The  following  are  some  of  the  important 
remarks  and  inferences  which  he  has  deduced  from  the  considera« 
tion  of  existing  phenomena,  and  of  the  degree  of  analogy  observa- 
ble between  ancient  and  modern  formations  : 

211.  "It  is  undeniable  that  many  objections  to  the  doctrine  of 
the  uniform  agency  of  geological  causes  have  been  partially  or 

What  objection  has  been  raised  to  the  supposition  that  changes  in  tho 
earth's  surface  are  due  to  causes  now  in  action  ? 

What  distinguished  writer  has  maintained  the. affirmative  of  that  hypo- 
thesis ? 

*  Outlines  of  the  Geology  of  England  and  Wales,  by  Conybeare  and 
Phillips,  pt.  i.  1822.  Introduction,  pp.  32,  33. 

t  Geol.  Man.,  pp.  148,  149. 

t  See  especially  Book  II.,  contained  in  the  1st  and  2d  vols.  of  tho  third 
edition. 


GEOLOGICAL  SPECULATIONS.  371 

entirely  removed  by  the  progress  of  the  science  in  the  last  forty 
years.  It  was  objected,  for  example,  to  those  who  endeavoured 
to  explain  the  formation  of  sedimentary  strata  by  causes  now  in 
diurnal  action,  that  they  must  take  for  granted  incalculable  periods 
of  time.  Now  the  time  which  they  required  has  since  become 
equally  requisite  to  account  for  another  class  of  phenomena 
brought  to  light  by  more 'recent  investigations.  It  must  always 
have  been  evident  to  unbiassed  minds,  that  successive  strata,  con- 
taining, in  regular  order  of  superposition,  distinct  beds  of  shells 
and  corals,  arranged  in  families  as  they  grow  at  the  bottom  of 
the  sea,  could  only  have  been  formed  by  slow  and  insensible  de- 
grees in  a  great  lapse  of  ages  :  yet,  until  organic  remains  were 
minutely  examined  and  specifically  determined,  it  was  rarely 
possible  to  prove  that  a  series  of  deposits  met  with  in  one  country 
was  not  formed  simultaneously  with  that  found  in  another. 
But  we  are  now  able  to  determine,  in  numerous  instances,  the 
relative  dates  of  sedimentary  rocks  in  distant  regions,  and  to 
show  by  their  organic  remains  that  they  were  not  of  contemporary 
origin,  but  formed  in  succession." 

212.  "  We  cannot  reflect  on  the  concessions  thus  extorted  from 
us,  in  regard  to  the  duration  of  past  time,  without  foreseeing  that 
the  period  may  arrive  when  part  of  the  Huttonian  theory  will  be 
combated  on  the  ground  of  its  departing  too  far  from  the  assump- 
tion of  uniformity  in  the  order  of  nature.  On  a  closer  investigation 
of  extinct  volcanos,  we  find  proofs  that  they  broke  out  at  suc- 
cessive eras,  and  that  the  eruptions  of  one  group  were  often  con- 
cluded long  before  others  had  commenced  their  activity.    Some 
were  burning  when  one  class  of  organic  beings  were  in  existence, 
others  came  into  action  when  a  different  and  new  race  of  animals 
and  plants  existed  :  it  is  more  than  probable,  therefore,  that  the 
convulsions  caused  by  subterranean  movements,  which  seem  to  be 
merely  another   portion  of  the  volcanic   phenomena,  have   also 
occurred  in  succession ;   and  their  effects  must  be  divided  into 
separate  sums,  and  assigned  to  separate  periods  of  time. 

213.  "  Nor  is  this  all :  when  we  examine  the  volcanic  products, 
whether  they  be  lavas  which  flowed  out  under  water  or  upon  dry 
land,  we  find  that  intervals  of  time,  often  of  great  length,  inter- 
vened between  their  formation,  and  that  the  effects  of  single  erup- 
tions were  not  greater  in  amount  than  those  which  now  result  from 
ordinary  volcanic  convulsions.     The  accompanying  or  preceding 
earthquakes,  therefore,  may  be  considered  to  have  been  also  suc- 
cessive, often  interrupted  by  long  intervals  of  time,  and  not  to 

How  has  the  objection  of  want  of  time  for  sedimentary  deposits  been 
met? 

What  data  have  we  for  determining  the  dates  of  sedimentary  rocks? 

How  do  the  known  facts  respecting  volcanos  prove  a  succession  of 
geological  eras  ? 

What  difference  in  the  products  of  volcanos  tends  to  establish  the  same 
general  truth  ? 


372  GEOLOGY. 

have  exceeded  in  violence  those  now  experienced  in  the  ordi- 
nary course  of  nature." — "  It  was  contrary  to  analogy  to  suppose 
that  nature  had  been  at  any  former  epoch  parsimonious  of  time  and 
prodigal  of  violence — to  imagine  that  one  district  was  not  at  rest, 
while  another  was  convulsed — that  the  disturbing  forces  were  not 
kept  under  subjection,  so  as  never  to  carry  simultaneous  havoc 
and  desolation  over  the  whole  earth,  or  even  over  one  great 
region."* 

214.  It  must  he  impossible  to  form  any  correct  judgment  as  to 
the  relative  probability  of  these  conflicting  estimates  of  the  in- 
fluence of  those  natural  causes  now  in  action  on  the  structure  and 
conformation  of  the  crust  or  exterior  portion  of  the  terrestrial 
globe,  without  a  previous  acquaintance  with  the  observations  that 
have  been  made  on  the  visible  phenomena  of  the  early  formations, 
and  the  displacements  and  modifications  to  which  they  have 
evidently  been  subjected.  Hence  it  will  be  requisite  to  take  some 
notice  of  the  great  convulsions  of  the  surface  which  have  left 
indelible  traces  of  their  occurrence;  and  also  to  give  a  brief  de- 
scription of  the  usual  appearances  of  rocks,  and  of  their  modes 
of  consolidation,  stratification,  and  juxtaposition. 

What  argument  in  favour  of  present  causes  is  afforded  by  the  Ameri- 
can lakes  ?  (Note.) 

How  is  the  objection  to  that  argument  answered  by  Boue? 

By  what  observations  may  we  be  enabled  to  judge  of  the  correctness 
of  any  theory  concerning  present  or  past  causes  of  change  in  the  eanifs 
crust  ? 

*  Prin.  of  Geol.,  vol.  i.  pp.  126 — 129.  As  an  argument  for  the  probability 
that  ancient  deluges  were  owing  to  causes  similar  to  ihose  now  in  opera- 
tion, Mr.  Lyell  observes  that  "  the  existence  of  enormous  seas  of  fresh 
water,  such  as  the  North  American  lakes,  is  alone  sufficient  to  assure  us, 
that  the  time  may  come,  however  distant,  when  a  deluge  may  lay  waste 
a  considerable  part  of  the  American  continent."  Mr.  Convbeare,  in  a 
paper  published  in  the  "  Annals  of  Philosophy,  1830  and  1831,"  endea- 
vours to  invalidate  the  reasoning  of  Mr.  Lyell,  by  a  comparison  of  the 
effect  produced  by  the  cataract  of  Niagara,  with  the  erosive  action  of  the 
current  of  the  Thames,  in  scooping  out  ihe  valley  through  which  it  flows, 
alleging  that  according  to  the  fluviatile  hypothesis  of  the  formation  of 
valleys,  that  of  the  Thames  must  have  been  hollowed  out  by  that  river,  in 
the  course  of  the  same  period  of  time  during  which  the  waters  of  the  lakes 
have  only  worn  a  channel  seven  miles  in  length.  But  M.  Boue  remarks, 
that  "  the  hollowing  out  of  the  valley  of  the  Thames  and  its  lateral  banks, 
commenced  not  merely  since  the  tertiary  epoch,  but  long  anterior  to  it, 
since  the  valley  traverses  very  different  formations;  while,  on  the  con- 
trary, the  cataract  of  Niagara  was  formed  in  the  alluvial  modern  or 
Jovian  period  of  M.  Brongniart."  Previously  to  that  epoch  he  alleges 
that  the  American  lakes  emptied  themselves  into  the  Mississippi,  and  that 
the  course  of  their  outlet  was  changed  by  volcanic  phenomena,  of  which 
there  are  still  some  traces  in  Canada  and  the  northern  United  States. 
See  a  French  translation  of  Mr.  Conybeare's  "  Examination  of  those  Geo- 
logical Phenomena  which  appear  to  have  the  most  immediate  Connection 
with  Theoretical  Opinions,"  by  M.  Boue,  with  Notes,  in  his  "  Memoires 
Ge"ologiques,"  vol.  i. 


NATURAL  AND  EXCAVATED  VALLEYS.  373 

Excavation  of  Valleys,  Denudation  of  Surfaces,  and  Elevation  of 
Mountains  and  Continents. 

215.  The  great  diversity  of  appearance  of  the  surface  of  the  earth 
is  caused  chiefly  by  the  occurrence  of  valleys  and  mountains  ;  and 
an  inquiry  into  the  circumstances  of  their  formation,  so  far  as  they 
can  be  ascertained  from  existing  appearances,  may  serve  materially 
to  enable  us  to  appreciate  the  nature  of  the  power  by  which  they 
were  originally  produced  or  subsequently  modified. 

216.  Valleys   have   sometimes   been   distinguished   into    two 
classes,  termed  natural  valleys  and  excavated  valleys.   The  origin 
of  the  former  is  ascribed   by  Werner  to   original   inequalities 
of  the  deposits  which  form  the  surface  of  the  earth.    Valleys 
of  this   kind  might  originate  from  the  gradual  desiccation  of  a 
lake  ;*  and  precipitations  of  solid  matter  from  the  water  might 
obviously  take  place,  without  causing  any  considerable  alteration 
of  the  figure   of  the   basin.     For   the   depositions,  might  form 
strata,  of  equal  thickness  on  the  bottoms  and  sides  of  the  cavity, 
so  as  only  to  lessen  its  size  ;  or  if  the  water  dried  away  very  gra- 
dually, the  deepest  deposit  would  be  in  the  centre,  and  the  basin 
might  still  preserve  nearly  the  same  outline. 

217.  It  may  easily  be  conceived,  however,  that  the  deposit  may 
be  so  arranged  as  to  cover  the  bottom  of  the  lake,  fill  up  any  irre- 
gularities, and  alter  more  or  less  the  form  of  the  cavity,  rendering 

it  shallower,  and 
in  place  of  a  deep 
lake,  leaving  a  val- 
ley  with  a  level 
surface  at  the  bot- 
tom. The  subjoined  figure  exhibits  sections  of  two  valleys  of  dif- 
ferent extent,  the  lighter  part  marking  the  outline  of  the  solid 
rock,  and  the  darker  the  deposits  of  gravel  and  detritus  which 
have  partly  filled  the  cavities.  Such  valleys,  where  the  super- 
ficial strata  are  undisturbed,  may  be  regarded  as  being  coeval 
with  the  formation  of  the  tract  in  which  they  are  situated. 

218.  Excavated  valleys,  or  valleys  of  erosion,  exhibit  very  dif- 
ferent appearances.  These  occur  in  hilly  and  mountainous  countries, 
while  the  former  may  be  found  in  the  midst  of  extensive  plains.  The 
excavation  of  valleys  may  take  place  under  a  variety  of  circum- 
stances, producing  corresponding  irregularities  of  conformation. 
When  strata  which  were  once  continuous  are  broken  and  swept 

How  have  valleys  been  distinguished  ? 

What  is  the  peculiar  character  of  the  first  class  1 

How  may  we  account  for  the  deposits  in  drained  lakes? 

How  do  valleys  of  erosion  differ  from  natural  valleys  ? 

*  For  a  case  of  this  kind  see  Mr.  R.  C.  Taylor's  Paper  on  the  Kisha- 
coquillas  valley,  in  Mifflin  county,  Pennsylvania.  Trans,  of  Geol.  Soc.  of 
Pa-,  vol.  i.  p.  194.— ED. 


374 


GEOLOGY. 


away  by  a  torrent  of  water,  if  the  beds  were  arranged  horizontally, 
the  opposite  sides  of  the  valley  would  present  similar  rocks  at 
the  same  elevation ;  while  the  alluvial  soil  or  looser  deposits 
would  form  the  summits  of  the  adjacent  eminences,  as  represented 

in  the  marginal  figure. 

219.  Sometimes,  however, 
the  appearances  are  very  dif- 
ferent. The  opposite  strata 
of  a  valley  not  being  arranged 
horiaontally,  but  inclined  at  a 
certain  angle,  beds  of  the 
same  rock  form  ascending  lines  on  one  side,  and  descending  lines 
on  the  other,  as  may  be  perceived  in  the  following  figure. 


In  this  section  it  will  appear,  that  the  stratum  ff,  which  forms  the 
summit  of  the  hill  on  one  side  of  the  valley  B,  descends  to  the 
basis  of  the  hill  on  the  opposite  side  of  the  same  valley.  Instances 
of  this  kind  not  unfrequently  occur;  and  they  are  obviously 
owing  to  the  different  beds  having  been  tilted  or  upraised  simul- 
taneously by  an  earthquake,  or  some  other  convulsion  of  nature, 
previously  to  the  scooping  out  of  the  valley  and  removal  of  those 
portions  of  once  continuous  strata  which  had  occupied  its  site. 

220.  When  the  beds  thus  cut  through  and  partially  swept 
away  consist  of  well  characterized  rocks,  such  as  would  be 
recognized  without  difficulty,  if  found  in  masses,  either  large  or 
small,  far  from  the  strata  still  remaining  in  situ  ,•  and  when  such 
shapeless  fragmeats  are  found  at  a  distance  from  the  former,  it 
may  naturally  be  concluded  that  they,  at  some  preceding  period, 
filled  the  now  open  space.  If,  then,  it  appears  that  these  de- 
tached masses  have  not  sharp  angles  and  edges,  but  are  worn  and 
rounded,  it  must  be  inferred,  especially  if  the  rock  be  hard  and 
compact,  that  the  blocks  or  pebbles  had  been  subject  to  violent 
attrition  against  each  other,  in  the  course  of  their  long  and  distant 
transport  j  and  that  the  same  deluge  that  had  occasioned  their 

How  may  valleys  of  erosion  exhibit  different  positions  of  the  original 
strata  ? 

What  inference  do  cases  pf  this  kind  enable  us  to  draw  in  regard  to  the 
relative  ages  of  river  beds,  arid  their  subjacent  rocky  strata? 

What  are  we  allowed  to  suppose  has  been  the  origin  of  water  worn 
Atones  in  the  beds  of  rivers  ? 


ERRATIC  ROCKS.  375 

disruption,  or  exposure  to  subsequent  action  of  a  similar  descrip- 
tion, had  reduced  them  from  an  angular  to  an  oval  or  globular 
shape,  like  the  water-worn  pebbles  on  the  sea-beach. 

221.  Now  there  are  to  be  met  with  in  many  countries  on  the 
surface  of  the  earth  masses  of  different  sizes,  and  of  every  variety 
of  rock ;  some  of  these  are  large  and  angular,  as  is  the  case  with 
the  vast  blocks  of  granite  strewed  over  the  surface  of  several 
parts  of  Germany,  and  which  have  been  referred  to  the  granitic 
chains  of  the  Norwegian  and  Swedish  mountains,  as  their  original 
position.    Other  portions  of  transported    matter  are   small   and 
rounded,  as  may  be  observed  with  respect  to  the  gravel  so  largely 
distributed  over  many  countries,  and  which  is  found  in  thick  and 
extensive  beds  in  England.    This  gravel  is  almost  entirely  flint, 
formerly  contained  in  the  chalk-strata,  which  seem  to  have  once 
covered  nearly  the  whole  of  the  south-eastern  part  of  that  country, 
from  some  districts  of  which  it  has  been  carried  away,  at  a  distant 
period,  by  a  great  flood  or  floods,  which  softened  and  washed  off 
the  lighter  chalk,  leaving  the  more  compact  and  heavier  flints 
behind. 

222.  Great  masses  of  rock  and  transported  gravel  are  found  in 
the  north  of  England.     Professor  Buckland  observed  among  the 
gravel  of  Durham  twenty  varieties  of  slate  and  greenstone,  which 
do  not  occur,  in  situ,  nearer  than  the  lake  district,  of  Cumberland. 
He  also  mentions  a  large  block  of  granite  at  Darlington,  of  the 
same  nature  with  that  at  Shap,  near  Penrith  ;  and  other  blocks  of 
this  granite  are  found  in  different  parts  of  Durham.*     Professor 
Sedgwick  notices  large  transported  bouldters  on  parts  of  the  Der- 
byshire chain  of  hills  overhanging  the  great  plain  of  Cheshire. 
He  observed  boulders  arid  pebbles  at  the  base  of  the  Cumberland 
mountains,  which  must  have  been  transported  across  the  Solway 
firth,  from  Dumfriesshire.     On  a  hill  near  Heytoncastle,  about 
four   miles   north-east  from   Maryport,  there   are  large  granitic 
boulders  resembling  the  rocks  of  the  Criffel ;  and  among  them  3 
spheroidal  mass,  in  one  direction  10  J  feet  in  diameter.    Vast  mul- 
titudes of  transported,  or,  as  they  have  been  termed,  erratic  blocks, 
are  found  scattered  over  the  northern  counties  of  England. 

223.  The  blocks  of  Shap  granite,  which  cannot  be  confounded 
with  other  rocks  in  the  north  of  England,  are  not  only  drifted  over 
the  hills  near  Appleby,  but  have  been  scattered  over  the  plain  ot 
the  new  red  sandstone ;  rolling  over  the  great  central  chain  of 
England  into  the  plains  of  Yorkshire  ;  imbedded  in  the  transported 
detritus  of  the  Tees ;  and  even  carried  to  the  eastern  coast. f 

224.  In  Scotland,  likewise,  such  blocks  abundantly  occur,  and 

To  what  source  are  the  blocks  of  granite  in  Germany  generally  referred? 
What  origin  is  assigned  to  beds  of  pebbles  and  gravel  ? 
What  facts  have  English  geologists  observed   in.  confirmation  of  this 
theory  ? 

*  Buckland's  Reliquiae  Diluvianae. 

t  De  la  Beche's  Geol.  Man.,  pp.  187,  188, 


376  GEOLOGY. 

in  some  remarkable  situations ;  as  in  the  Shetland  islands,  where 
there  are  boulders,  which  do  not  correspond  with  any  known  rock  in 
the  country,  and  which  were  probably  derived  from  the  northward. 
It  seems  likewise  that  similar  phenomena  are  observable  in  the 
Feroe  islands.* 

•225.  "  The  probability,  therefore,"  says  Mr.  De  la  Beche,  "as 
far  as  the  above  facts  seem  to  warrant,  is,  that  masses  of  water 
have  proceeded  from  north  to  south  over  the  British  isles,  moving 
with  sufficient  velocity  to  transport  fragments  of  rock  from  Nor- 
way to  the  Shetland  isles  and  the  eastern  coast  of  England  ;  the 
course  of  such  masses  of  water  having  been  modified  and  obstructed 
among  the  valleys,  hills,  and  mountains,  which  they  encountered; 
so  that  various  minor  and  low  currents  having  been  produced,  the 
distribution  of  detritus  has  been  in  various  directions." 

226.  The  continents  both  of  Europe  and  North  America,  fre- 
quently present  analogous  phenomena  of  erratic  blocks  and  trans- 
ported gravel.  It  is  difficult  to  account  for  the  occurrence  of  erratic 
blocks,  particularly  in  certain  situations,  from  which  it  must  be 
inferred,  that  they  have  been  carried  across  the  sea,  and  some- 
times to  great  distances.    It  has  been  conjectured  that  these  mas- 
sive bodies  might  have  been   imbedded   in  ice,  and    thus  con- 
veyed by  currents  which  would  have  failed  to  remove  them  had 
not  their  specific  gravity  been  thus  diminished.  Other  hypotheses 
have  been  proposed  to  account  for  these  phenomena,  but  they  are 
not  sufficiently  probable  to  require  further  notice ;  and  we  shall 
only  remark,  in  the  words  of  a  distinguished  writer,  that  "  solu- 
tions of  the  problem  of  erratic  blocks  seem  not  very  practicable  at 
present." 

227.  In  some  districts,  immense  tracts  of  strata,  several  hundred 
feet  in  thickness,  have  been  torn  from  the  surface,  and  the  mate- 
rials all  carried  off,  except  some  occasional  patches,  forming  the 
caps  of  isolated  hills,  the  analogous  composition  of  which  shows 
that  they  were  once  parts  of  a  continuous  formation.     These  ex- 
tensive removals  of  superficial  strata  have  been  termed  denuda- 
tions, of  which  phenomena  Great  Britain  presents  numerous  in- 
stances ;  one  of  the  most  remarkable  of  which  is  that  called  the 
denudation  of  the  valley  of  the  Weald,  including   the  district 
between  the  north  and  south  Downs,  chiefly  in  the  county  of 
Sussex.     The   geology  of  this  tract  has  been  rendered  highly 
interesting  by  the  researches"  and  important  discoveries   of  Mr. 
Mantell,  relative  to  the  fossil  remains  imbedded  in  some  of  the 
strata  ;  which  will  be  subsequently  noticed.    The  Wealden  coun- 
try is  bordered  on  three  sides  by  chalk  hills,  which  terminate 

What  is  inferred  to  have  been  the  direction  of  the  currents  which 
transported  the  boulders  found  in  Great  Britain  ? 

What  suppositions  have  been  advanced  to  account  for  the  presence  of 
erratic  blocks  at  great  distances  from  their  original  situations  ? 

What  is  meant  by  denudation,  in  geology  ? 

*  Dr.  Hibbert,  in  Edinb.  Journ.  of  Science,  vol.  vii. 
t<Jeolog.  Man.,  p.  189 


ELEVATION  01"  MOUNTAINS.  377 

abruptly  on  its  confines,  and  which  appear  to  have  <  -^ce  extended 
over  the  intermediate  space.  Professor  H.  D.  Rogers  in  his  recent 
reconnoissance  of  the  Geology  of  New  Jersey  has  discovered  what 
he  conceives  to  he  evidence  that  the  lower  and  maratime  portions 
of  that  state  have  undergone  the  process  of  denudation,  having 
only  here  and  there  a  bluff  or  crag  formed  of  entirely  different 
materials  from  those  of  the  general  surface  of  that  region.* 

228.  The  origin  of  valleys  has  sometimes  been  attributed  to  those 
convulsions  of  the  earth  which  occasion  the  elevation  of  mountain 
ridges  ;  and  some  valleys  must  doubtless  have  been  thus  produced, 
however  they  have  been  subsequently  modified  by  the  action  of 
the  atmosphere  or  of  running  water.     "  If  the  crust  of  the  globe 
were  broken,  and  raised  in  parallel  ridges,  they  might  form  moun- 
tain ranges,  with  valleys  between  them,  like  what  are  observed 
bordering  the  central  range  of  the  Alps;  the  arched  stratification 
of  many  of  the  calcareous  mountains,  and  the  vertical  position  of 
the  beds,  favours  this  hypothesis." 

229.  The  production  of  mountains  has  been  ascribed  to  different 
causes;  but  the  most  obvious  and  important  seems  to  be  elevation 
in  consequence  of  some  force  acting  from  beneath.     Volcanic  ac- 
tion has  in  numerous  instances  formed  mountain  cones  and  peaks, 
consisting  of  deposits  of  scoriae,  ashes,  and  lava.     But  there  are 
many  situations  in  which  granitic  and  other  primary  rocks,  con- 
stituting in  general  the  lowest  strata  of  the  crust  of  the  globe, 
have  been  raised  in  a  solid  state,  so  as  now  to  form  the  summits 
of  lofty  mountains.     Long  chains  or  ridges  of  hills,  which  occur 
in  various  parts  of  the  world,  cannot  originate  from  the  immediate 
influence  of  volcanic  eruptions.     Such  elevations  of  solid  matter, 
and  extensive  ridges,  therefore,  must  be  supposed  to  be  owing  to 
the  operation  of  causes  such  as  those  which  occasion  earthquakes, 
or  rather,  in  fact,  to  be  the  result  of  earthquakes  taking  place  on 
a  most  stupendous  scale. 

230.  The  manner  in  which  the  more  dense  and  solid  masses  of 
primary  rocks  may  be  forced  up,  and  made  to  break  through  the 
less  compact  strata  of  clay,  gravel,  or  other  substances,  by  pres- 
sure from  below,  and  thus  form  the  summit  of  a  mountain  ridge, 

may  be  understood 
from  the  marginal  fU 
gure.  Here  the  irre- 
gular conical  mass 
in  the  centre,  which 
may  be  supposed  to 
be  granite,  gneiss,  or 

To  what  is  the  origin  of  natural  valleys  attributed  by  geologists  ? 
In  what  direction  must  the  forces  have  acted  which  produced  the  pre- 
sent mountains  ? 

What  classes  of  mountains  may  be  referred  to  volcanic  action  ? 

*  These  views  were  communicated,  by  Professor  R.,  to  the  Academy  of 
Nat.  Science,  of  Philadelphia,  Nov.,  1835.— ED. 

9.i  2 


378  GEOLOGY. 

primary  limestone,  is  represented  as  having  burst  asunder  the 
superior  strata,  which  now  form  the  sides  of  the  mountain. 
Wherever  strata,  originally  horizontal,  exhibit  a  vertical  or  highly- 
inclined  position,  the  sudden  and  violent  operation  of  an  elevating 
force  may  be  inferred  ;  and  where  mountains  are  raised  to  a  con- 
siderable height,  and  preserve  an  unbroken  range  of  nearly  hori- 
zontal strata,  it  must  be  concluded  that  the  upheaving  force  was 
slow  in  its  operation,  or  acted  on  a  large  segment  of  the  earth's 
surface. 

231.  The  elevation  of  large  continents  and  entire  islands  must, 
like  that  of  mountains,  have  been  owing  to  the  action  of  a  force 
from  below ;  but  the  magnitude  of  the  effect  produced,  and  the 
difference  of  the  phenomena,  show  that  there  must  have  been  a 
considerable  diversity  in  the  mode  of  operation.     Probably  all 
large  tracts  of  country  or  continents  emerged  slowly  from  the 
ocean,  at  first  forming  islands,  before   the   lower  tracts  were 
raised  above  the  level  of  the  sea. 

232.  The  power  requisite  to  upheave  a  continent,  or  in  other 
words,  to  cause  the  protrusion  of  a  large  portion  of  the  solid  surface 
of  the  earth,  must  be  very  different  from  the  force  which,  acting 
in  certain   lines,  occasioned    the   elevation  of  mountain  ranges. 
England  affords  instances  of  the  apparent  difference  between  the 
modes  of  action  of  those  forces  which  raised  ridges  of  hills,  and 
those  which  elevated  continents  or  extensive  islands. 

233.  "  The  elevating  force  that  broke  and  tilted  up  the  chalk 
strata  and  the  tertiary  strata,  along  a  line  extending  east  and  west 
through  the  Isle  of  Wight,  into  Dorsetshire,  does  not  appear  to 
iiave  produced  any  .considerable  change  on  each  side  of  the  line. 
In  passing  from  Alum  bay,  where  the  chalk   strata  are  nearly 
vertical,  to  the  south  side  of  the  island,  it  is  truly  extraordinary 
to   observe   how  little   the  lower  beds  beneath    the  chalk,  and 
adjacent  to  it,  appear  to  have  been  disturbed.     The  force  which 
uptilted  the  strata  is  altogether  distinct  from  that  mighty  upheaving 
force  which  raised  the  whole  chalk  hills  in  the  south  of  England 
from  the  ocean,  without  disturbing  the  relative  position  of  the 
strata."* 

234.  Some  extraordinary  elevations  of  land  are  said  to  have 
taken  place  at  very  recent  periods.  Von  Hoff  states,  that  in  1771, 
several  tracts  of  land  .were  upraised  in  Java,  and  that  a  new  bank 
made  its  appearance  opposite  the  mouth  of  the  river  Batavia.     It 
has  also  been  asserted,  that  it  appeared  on  the  morning  after  the 
earthquake  in  Chili,  in  1822,  that  "  the  whole  line  of  coast,  from 

How  are  we  to  distinguish  those  mountains  which  have  proceeded  from 
sudden,  from  those  which  resulted  from  gradual  upheaving  ? 

in  what  manner  did  the  more  extensive  tracts  of  land  probably  ri«e  from 
the  ocean  ? 

What  examples  of  the  different  kinds  of  upheaving  are  found  in  England  ? 

*  Bakewell'g  Introd,  to  Geol.,  pp.  500,  501. 


CHRONIC  ELEVATION  OF  LAND.  379 

north  to  south,  to  the  distance  of  above  100  miles,  had  been  raised 
above  its  former  level."  The  accuracy  of  the  observations  on 
which  these  statements  are  founded  have,  however,  been  questioned 
by  Mr.  Greenough  :  but  this  celebrated  geologist  admits  that  it  is 
a  point  deserving  of  consideration,  "  whether  there  may  not  be 
going  on,  in  the  calmest  season  and  in  the  stillest  countries,  a 
chronic  and  almost  imperceptible  impulsion  of  land  upwards  /"  and 
he  refers  to  the  researches  of  the  Swedish  philosophers  concerning 
the  decreasing  height  of  the  waters  of  the  Baltic,  as  affording  some 
evidence  that  such  an  operation  is  in  progress.* 

235.  The  evidences  of  both  elevation  and  depression,  in  former 
times,  are  abundantly  demonstrative.     The  occurrence  of  beds  of 
oysters  and  other  sea-shells  on  the   tops  of   mountains  and  on 
elevated  plains,  shows  that  the  land  must  at  some  distant  period 
have  been  submerged ;  and  the  remains  of  forests  seen  beneath  the 
surface  of  the  sea,  indicate  the  changes  that  have  taken  place  of 
a  contrary  description.  It  is  manifest,  then,  that  some  portions  of 
the  earth's  surface  have  been  depressed,  and  what  was  once  dry 
land  has  become  the  bed  of  the  sea ;  while  other  parts,  formerly 
covered  by  its  waters,  and  resorted  to  by  marine  Crustacea,  have 
been  since  upheaved  into  hills  and  mountain  ridges,  thickly  strown 
with  the  exuviae  of  their  ancient  inhabitants. 

236.  The  earth  seems  to  be  subject  to  a  kind  of  oscillation  of 
surface  ;  one  area  of  which  may  be  reduced  below  the  level  of  the 
ocean  at  one  period,  and  another  at  another.     All  the  rocks  which 
have  originated  since  this  globe  became  the  scene  of  organic  life, 
afford  evidences  of  their  having  been  deposited  under  a  liquid, 
except  the  volcanic  and  trap  rocks,  the  igneous  origin  of  which 
cannot  be  doubted.     That  granite,  gneiss,  primitive  quartz,  and 
limestone,  with  the  other  non-fossiliferous  rocks,  were  produced  in 
the  same  manner  with  those  last  mentioned,  may  also  be  admitted 
as  at  least  probable.     These  rocks  form,  as  it  were,  the  skeleton 
or  basis  of  the  solid  crust  of  the  earth,  and  they  appear  to  be  the 
most  widely  and  continuously  distributed.     In  the  rocks  of  this 
class  are  chiefly  found    the   metallic   ores  and    more   valuable 
minerals.     The  superior  rocks  or  strata  are  more  especially  in- 
teresting on  account  of  the  bodies  they  contain,  either  curious  or 
useful,  derived  from  organic  matter. 

What  is  the  nature  of  the  facts  which  prove  the  elevation  and  depres- 
sion of  portions  of  the  earth's  surface  ? 

What  classes  of  rocks  on  the  earth's  surface  appear  to  have  originated 
from  aqueous  deposits  ? 

What  was  the  probable  origin  of  the  non-fossiliferous  rocks  ? 

*  See  the  Athenaeum  Journal  for  June  14,  1834,  No.  346,  for  interesting 
extracts  from  the  address  delivered  by  Mr.  Greenough,  as  President,  to  the 
Geological  Society,  at  their  last  meeting  of  the  session,  June  4. 

For  the  Reply  of  Mrs.  Graham  to  Mr.  Greenough,  respecting  the  above 
address,  see  the  American  Journal  of  Science,  vol.  xxviii.,  p.  236. — ED. 


380  GEOLOGY. 

General  Structure  and  Composition  of  Rocks,  and  their  .Modes  of 
Juxtaposition. 

237.  The  different  kinds  of  rocks   may  be  distinguished   as 
respects  their  mineralogical  composition  and    their   mechanical 
structure.     Considered  as  mineral  bodies,  they  are  either  simple 
or  compound.     Thus  there  are  some  that  consist  essentially  of  a 
single  mineral,  as  quartz  rock,  which  is  composed  of  quartz  or 
siliceous  earth;  and  primitive  limestone,  and  chalk,  which  both 
consist  of  carbonate  of  lime. 

238.  The  minerals  that  enter  into  the  composition  of  rocks  are 
by  no  means  numerous;  and  of  these  the  most  important  are  in- 
cluded in  the  following  catalogue  :* 

1.  Argillaceous  earth,  (indurated  clay,)  [258 — No.76.]f 

2.  Siliceous  earth,  (quartz,)  [059 — No.  80.] 

3.  Steatite,$  [261— No.  87.] 

4.  Feldspar,  [262— No.  92.] 

5.  Albite,  or  cleavelandite,  [263 — No.  92.] 

6.  Mica,  [263— No.  93.] 

7.  Chert,  or  hornstone,  [259 — No.  82.] 

8.  Pitchstone,  [262— No.  90.] 
•9.   Talc,  [263— No.  93.] 

10.  Chlorite,  [263— No.  93.] 

11.  Hornblende,  [263— No.  94.] 

12.  Serpentine,  [264— No.  95.] 

13.  Actinolite,  [263— No.  94.] 

14.  Augite,  [264— No.  97.] 

15.  Dlallage,  [264— No.  97.] 

16.  Hypersthene,  [264— No.  97.] 

17.  Garnet,  [264— No.  99.] 

18.  Schorl,  [266— No.  103.] 

19.  Carbonate  of  lime— chalk,  [271— No.  123.] 

20.  Carbonate  of  magnesia,  [274 — No.  131.] 

21.  Gypsum,  [278— No.  147.] 

22.  Oxide  of  iron. 

23.  Bitumen. 

24.  Coal. 

What  mineralogical  differences  dp  rocks  present? 
Enumerate  the~most  important  minerals  found  in  rocks? 

*  See  Dr.  Macculloch's  Geological  Classification  of  Rocks,  1821,  p.  166; 
and  Phillip's  Outlines  of  Mineralogy  and  Geology,  p.  83. 

t  The  numbers  annexed  to  the  names  of  the  different  minerals  indicate 
the  pages  and  sections  of  the  preceding  treatise  on  Mineralogy,  in  which 
they  are  respectively  described. 

t  Those  minerals,  the  names  of  which  are  printed  in  italics,  are  com- 
paratively of  unusual  occurrence,  or  are  found  in  relatively  small  propor- 
tions in  those  rocks  of  which  they  are  ingredients. 


GRAPHIC  GRANITE.  381 

239.  Besides  some  of  the  minerals  in  the  preceding  list,  Mr. 
Phillips  mentions  the  following,  as  being  sometimes  interspersed 
in  rocks,  or  occasionally  forming  masses  in  them  :  iron  pyrites,  sul- 
phuret  of  molybdena,  oxidulated  iron,  oxide  of  tin,  flint,  calcedony, 
jasper,  obsidian,  calcareous  spar,  dolomite,  and  arsenical  iron.  The 
same  writer  has  given  a  list  of  minerals  most  frequently  occurring 
in  veins.    These  are  carbonate  of  barytes,  phosphate  of  lime,  sul- 
phate of  barytes,  selinite,  and  fluor  spar ;  besides  several  ores  of 
iron,  manganese,  copper,  lead,  and  zinc,  information  concerning 
which  may  be  found  in  the  treatise  on  Metallurgy  and  Mining  in 
this  volume. 

240.  It  will  appear  from  the  preceding  statements,  that  the 
mineral  substances  which  contribute  most  largely  to  the  composi- 
tion of  rocks  amount  to  about  a  dozen  ;  and  these  must  obviously 
deserve  the  principal  attention  of  the  geologist.     Those  that  are 
more  rare  should  not,  however,  be  neglected,  as  their  presence 
sometimes  serves  to  identify  particular  kinds  of  rocks,  ana  furnish 
their  discriminating  characters. 

241.  The  interest  and  importance  of  the  various  rocks  to  the 
geologist  depends  greatly  on  their  relative  situation,  as  contributing 
to  form  the  crust  of  the  earth.     Of  all  the  lower,  or  as  they  are 
termed,  primitive  rocks,  the  most  important  is  granite,  which  is 
considered  as  a  compact  or  non-stratified  rock,  and  is  thus  dis- 
tinguished from  gneiss,  the  mineral  composition  of  which  is  similar, 
but  which  is  composed  of  distinct  strata,  and  has  been  therefore 
sometimes  styled  stratified  granite  or  granitic  slate.     "  Granite," 
according  to  Mr.  de  la  Beche,  "  is  a  confusedly  crystalline  com- 
pound of  quartz,  feldspar,  mica,  and  hornblende."     But  there  are 
various  kinds  of  granite,  some  rocks  thus  denominated  containing 
only  feldspar  and  mica,  others  feldspar  and  quartz,  feldspar  and 
hornblende,  or  quartz  and  hornblende.  But  though  all  such  might 
be  termed  granitic  rocks,  the  appellation  of  granite  should  rather 
be  restricted  to  compounds  of  feldspar,  quartz,  and  mica.     This 
rock,  forming  a  most  excellent  architectural  material,  has  been 
abundantly  used  in  the  buildings  and  pavements  of  cities,  so  that 
its  general  appearance  needs  not  to  be  described. 

242.  In  some  specimens  of  granite  the  three  characteristic  mi- 
nerals are  in  very  small  crystals,  intimately  and  generally  blended 
into  a  grey  mass  ;  in  others,  on  the  contrary,  the  crystals,  particu- 
larly those  of  the  feldspar,  are  extremely  large,  and  in  greater  pro- 
portion than  common.     Red  granite,  which  is  found  in  Scotland, 
contains  much  feldspar,  which  is  of  a  red  or  flesh  colour,  instead 
of  being  white,  as  usual.     Graphic  granite  consists  of  quartz  and 
feldspar  only,  the  crystals  of  the  latter  being  so  distributed 

To  what  circumstance,  in  regard  to  a  rock,  does  the  geologist  attach  the 
highest  importance?    What  is  the  difference  between  granite  and  gneiss? 
What  minerals  enter  into  the  composition  of  granite  ? 
What  varieties  of  this  rock  are  known  to  exist? 
To  what  purposes  is  granite  peculiarly  adapted  ? 
What  is  the  composition  of  graphic  granite  ? 


382  GEOLOGY. 

amidst  those  of  the  quartz,  as  to  give  the  surface  of  the  rock, 
when  broken,  the  appearance  of  being  covered  with  antique 
characters. 

243.  Diallage  rock  consists  either  of  the  mineral  from  which 
it  takes  its  name  alone,  or  of  diallage  and  feldspar,  forming  a  gra- 
nular crystalline  compound.    The  former  variety  is  rare,  but  the 
latter  abounds  in  some  of  the  Shetland  islands.     There  are  other 
varieties,  which  contain  actinolite,  talc,  chlorite,  quartz,  or  mica. 

Greenstone  is  a  granular  rock,  chiefly  composed  of  hornblende 
and  feldspar,  but  sometimes  including  quartz,  and  occasionally 
calcareous  spar. 

244.  Serpentine   consists   essentially  of  the  mineral    of  that 
name,  but  sometimes  contains  hornblende,  and  also  veins  of  stea- 
tite, talc,  or  asbestus.     It  is  commonly  of  a  dark  green  colour, 
intermixed  with  red,  with  waving  lines,  and  convolutions  on  its 
surface. 

245.  Syenite  is  a  compound  of  feldspar,  hornblende,  and  quartz, 
confusedly  aggregated,  the  former  generally  predominating.     It 
derives  its  name  from  Syene  in  Upper  Egypt,  where,  however, 
it  is  said,  the  rock  is  of  a  different  nature.     It  is  usually  very 
hard,  and  of  a  dull  red  colour,  but  it  is  sometimes  grey,  or  dark 
green. 

246.  Among   the  other  unstratified  rocks   may  be   mentioned 
schorl   rock,   composed    of  schorl  and  quartz,  and  hypersthene 
rock,  containing  feldspar  or  albite,  and  sometimes  quartz. 

246.  Porphyritic   rocks  vary    in   composition,   but   they    are 
usually  of  a  reddish  or  purple  colour,  and  contain  crystals  im- 
bedded in  a  mineral  mass,  as  if  they  had  been  enclosed  when 
it  was  in  a  semifluid  state.     "  Porphyries  are  generally  known 
by  the  name  of  the  base  or  paste  which  includes  the  Disseminated 
crystals:    thus   we   have  claystone   porphyry,   feldspathic   por- 
phyry, and  clinkstone  porphyry."* 

247.  The  stratified  rocks  are  commonly  supposed  to  have  been 
formed  from  the  detritus  of  the  unstratified  rocks,  taken  up  and 
afterwards   deposited  by  water ;  unless  where  they  consist   of 
single  minerals,  as  limestone  and  quartz,  which  must  have  been 
produced   by   chemical   precipitation.      The   following  are    the 
inferior  stratified  or  non-fossiliferous  rocks  described  by  Mr.  De 
la  Becherf  Argillaceous  or  clay  slate,  chlorite  slate,  talcose  slate, 
quartz  rock,  hornblende  rock  and  slate,  primitive  limestone,  com- 
pact feldspar,  or  eurite,  mica  slate,  gneiss,  and  protogine.     The 
nature  and  general  composition  of  most  of  these  rocks  is  indi- 

How  is  diallage  rock  characterized  ? — greenstone  ? — serpentine  ? — sye 
nite? 

What  is  the  composition  of  schorl  rock  ? 

By  what  circumstance  are  the  different  kinds  of  porphyry  distinguished  1 
How  do  geologists  account  for  the  origin  of  stratified  rocks  ? 
Enumerate  the  non-fossiliferous  rocks? 

*  De  la  Beche's  Geol.  Man.,  p.  447.  t  See  Geol.  Man.,  sect.  x. 


LIAS.  383 

cated  by  their  appellations ;  gneiss,  as  before  stated,  is  a  strati- 
fied or  schistose  granite,  and  protogine  differs  from  it  only  in 
containing  talc  or  steatite,  instead  of  mica. 

248.  The  superior  rocks  may  here  be  dismissed  with  a  cursory 
notice.     Grauwacke,  or  graywacke,*  has  been  described  as  an 


aggregate  cemented  by  ferruginous  clay,  and  composed  of  the 
debris  of  the  primitive  rocks. "f  The  inclosed  fragments  are 
sometimes  small  and  granular  and  sometimes  as  large  as  a  nut. 

249.  Transition  limestone  is  so  named  to  discriminate  it  from 
the  other  calcareous  rocks,  and  particularly  from  the  inferior  or 
primitive  limestone.     The    term   transition   is  derived  from  the 
school  of  Werner,  who  regarded  all  rocks  as  having  been  pro- 
duced by  deposition  from  a  liquid,  and  considering  those  which 
contain  no  organic  remains,  (as  granite  or  gneiss,)  to  be  the  oldest, 
he  gave  the  appellation   of  transition  rocks  to  the   immediately 
superincumbent  masses,  in  which  occur  remains  of  zoophytes,  and 
other  petrifactions  of  the  relics  of  the  lower  orders  of  organized 
beings,  but  none  of  vertebrated  animals,  or  of  any  of  the  higher 
orders.   Hence,  also,  he  concluded  that  the  rocks  thus  constituted 
were  formed  while  the  earth  was  in  a  state  of  transition  from  a 
comparatively  uninhabitable  to  an  inhabitable  condition.     Among 
the  calcareous  rocks,  also,  are  carboniferous  limestone,  magnesian 
limestone,  and  muschelkalk,  or  shell  limestone. 

250.  Red  sandstone  exhibits  great  diversity  of  texture,  some- 
times forming  a  reddish  or  variegated  marl  or  clay,  and  sometimes 
compact  stony  masses ;  in  either  case  exhibiting  streaks  of  light 
blue,  verdigris,  or  cream  colour. 

51.  Shale  includes  all  the  argillaceous  schists  of  the  secondary 
class,  sometimes  improperly  called  slate  clay.  These  rocks  seldom 
form  extensive  beds,  but  are  found  in  thin  strata,  often  of  mere 
laminae,  alternating  with  the  other  rocks  with  which  they  are  as- 
sociated. Shale  occurs  together  with  coal,  with  which  it  like- 
wise alternates,  and  it  frequently  contains  organic  remains.}: 

252.  Lias  is  a  term  derived  from  the  English  miners,  to  denote 
an  argillo-calcareous  deposit,  occurring  in  England  and  other  parts 
of  Western  Europe,  above  the  red  sandstone,  and  below  the  chalk, 
forming,  according  to  the  arrangement  of  Mr.  De  la  Beche,  a  por- 
tion of  the  oolitic  group,  so  called  from  the  oolite,  or  roestone,§ 

What  is  the  nature  of  grauwacke  ? 

Whence  does  transition  limestone  derive  its  name? 

What  classes  of  fossils  are  found  in  that  rock  ? 

fn  what  variety  is  red  sandstone  found  ? 

What  is  meant  by  shale  ? 

What  is  the  situation  of  lias? 

*  The  rock  was  thus  named  by  a  German  miner,  who  was  accustomed  to 
term  every  rock  he  was  unacquainted  with  wacM,  and  he  distinguished 
this  by  the  epithet  grau,  gray,  from  its  colour. 

t  Mawe's  Familiar  Lessons  on  Mineralogy  and  Geology.  12th  edition- 
1830.  p.  78. 

t  See  Dr.  Macculloch  on  the  Classification  of  Rocks,  pp.  455 — 463. 

$  See  Treatise  on  Mineralogy,  No.  127. 


384  GEOLOGY. 

which  constitutes  the  upper  part  of  the  group,  while  the  lias  forms 
its  base. 

253.  The  trap,  or  overlying  rocks,  are  unstratified,  and  are  sup- 
posed to  be  the  products  of  ancient  volcanos.     They  occur   in 
masses,  generally  irregular,  and    in    outline  presenting  the  ap- 
pearance of  steps,  whence  the  appellation  of  trap,  which  is  of 
Swedish  origin.  .    Dr.  Macculloch  calls    them  overlying  rocks, 
doubtless  because  they  are  in  most  instances  found  resting  on  al- 
most every  other  kind  of  rock,  from  chalk  to  granite.     They  are 
abundant,  and   sometimes  form  considerable  mountains,  though 
upon  the  whole  they  are  of  more  limited  extent  than  the  stratified 
rocks. 

254.  Basalt  is  a  designation  applied  to  various  dark-coloured 
rocks,  of  a  close  fine-grained  texture.     It  resembles  greenstone, 
and  some  writers  describe  it  as  composed  almost  wholly  of  horn- 
blende, others  of  augite,  feldspar,  and  titaniferous  iron.  Olivine  is 
sometimes  contained  in  it,  and  also  quartz,  calcedony,  calcareous 
earth,  and  other  substances.  Basalt  exhibits  a  columnar  structure, 
and  becomes  porous  on  the  exterior  surface,  from  partial  decom- 
position. 

255.  Wacke  resembles  indurated  clay,  often  highly  ferruginous, 
and  is  either  compact  or  cellular.     It  appears  to  be   basalt,  in 
a  state  of  decomposition.     Graystone,  porphyry  slate,  and  clink- 
stone have  been  considered  as  varieties  of  either  basalt  or  green- 
stone. 

Trachyte  is  generally  composed  of  feldspar,  and  sometimes  con- 
tains albite.  It  is  chiefly  porphyritic,  from  included  crystals  of 
hornblende,  mica,  augite,  sphene,  and  sometimes  other  mine- 
rals. 

256.  Amygdaloid  is  a  trap  rock,  the  basis  of  which  is  indurated 
clay,  or  compact  feldspar.     Various  minerals,  as  agate,  quartz, 
mesotype,  analcime,  stilbite,  prehnite,  carbonate  of  lime,  green 
earth,  lithomarge,  and  iron  pyrites,  are  occasionally  imbedded  in 
this  rock,  rendering  it  porphyritic ;  and  their  disintegration  or  de- 
composition, produces  a  vesicular  structure,  giving  it  the  appear- 
ance of  cellular  lava. 

Pitchstone,  which  is  considered  by  some  as  a  semivitrified 
basalt,  has  been  found  to  contain  a  considerable  proportion  of 
bitumen. 

257.  Cornean  is  a  term  which  has  been  used  to  denote  a  kind 
of  rock,  the  composition  of  which  appears  to  be  undetermined. 
It  sometimes  approaches  to  the  characters  of  basalt,  being  very 
hard,  and  in  other  cases  more  closely  resembles  wacke.     Brong- 
niart  conceived  it  to  be  the  basis  of  the  Derbyshire  toadstone. 

Traptuff  is  composed  of  the  debris  of  the  other  rocks  of  this 

What  is  the  appearance  of  trap  rocks  ? 

Why  are  they  termed  overlying  ? 

What  is  the  appearance,  composition,  and  structure  of  basalt  ? 

Of  what  is  trachyte  composed  ? — amygdaloid  ? 

To  what  is  the  term  cornean  applied  ? 


STRATIFIED  ROCKS.  385 

class,  united  by  an  argillaceous  cement,  and  forming  a  coarse 
breccia. 

258.  The  principal  compounds  which  are  the  products  of  modern 
volcanos  are  porphyritic  and  basaltic  lavas,  obsidian  or  volcanic 
glass,  pumice  or  porous  lava,  volcanic  conglomerate,  and  volcanic 
tufa.    The  minerals  contained  in  these  more  recent  igneous  rocks 
have  been  already  noticed. 

259.  The  mechanical  structure  of  rocks  admits  of  distinctions 
with  regard  to  their  internal  texture,  or  their  external  appearance. 
It  will  be  sufficient  to  enumerate  the  designations  of  interior 
structure  by  which  different  rocks  are  characterized.     These  are 
the  stony,  compact,  earthy,  granular,  fibrous,  lamellar,  foliated, 
schistose,    cellular,    prismatic,   amygdaloidal,   porphyritic,   and 
conglomerated  varieties  of  conformation. 

260.  With  reference  to  their  exterior  structure  and  appearance, 
rocks  might  be  distinguished  into  those  which  are  symmetrical, 
and  those  which  are  amorphous.  Both  these  terms,  however,  must 
be  employed  with  a  considerable  degree  of  latitude.     Among  the 
symmetrical  rocks   may  be  reckoned  those  which  are  stratified, 
tabular,  or  columnar;  and  all  the  other  descriptions  of  rocks  may 
be  regarded  as  amorphous,  or  rather  polymorphous,  their  external 
forms  depending  on  incidental  circumstances. 

261.  Stratified  rocks  are  those  in  which  masses  of  similar  com- 
position, as  clay  slate  or  sandstone,  extend  through  a  hill  or  moun- 
tain in  nearly  parallel  layers  or  strata.     They  display  in  different 
situations  great  varieties  of  arrangement  and  juxtaposition.  Some- 
times the  strata  which  form  a  rocky  eminence  are  placed  in  flat 

horizontal  masses,  one 
above  another.  The  mar- 
ginal figure  may  be  sup- 
posed to  represent  a  hill, 
the  base  of  which  is  com- 
posed of  granite,  E ;  on 
which  rests  a  stratum  of 
gneiss  or  mica-slate,  D ; 
supporting  one  of  sand- 
stone, C  ;  having  above  it  another  of  chalk  with  imbedded  nodules 
of  flint,  B  ;  crowned  by  clay,  gravel,  or  any  alluvial  mater,  A. 

262.  Sometimes  the  strata  composing  rocks  are  inclined  at  angles 
more  or  less  acute,  varying  from  the  horizontal  to  the  vertical 
position.     In   some  situations  the  strata  take  a  waving  course, 
rising  with  the  undulating  surface  of  the  hills  on  one  side,  and 
declining  on  the  other,  in  the  manner  represented  in  the  annexed 
diagram. 

What  are  the  products  of  modern  volcanos  ? 
What  terms  apply  to  the  internal  mechanical  structure  of  rocks? 
What  two  names  denote  their  differences  of  external  structure  ? 
To  what  does  the  term  stratified  rocks  appropriately  belong  ? 
Enumerate  the  strata  frequently  found  in  succession,  beginning  with 
the  surface  soil. 

2K 


386 


GEOLOGY. 


263.  Contortions  or  sinuosities  of  strata,  of  a  much  more  abrupt 
character,  are  also  common  in  mountain  ranges,  indicating  the 
peculiar  operation  of  extraordinary  force  in  their  formation.  "  Con- 
tortion requires  that  the  rocks  in  which  it  is  observable  should 
have  been  in  a  yielding  state,  and  that  the  particles  were  capable 
of  a  certain  movement  among  themselves,  so  that  when  force  was 
applied  no  absolute  fracture  was  occasioned.    Sir  Jarnes  Hall  has 
long  since  shown,  that  to  produce  contortion  by  lateral  pressure, 
there  must  be  resistance  both  above  and  beneath,  the  former  at 
least  being  capable  of  yielding  in  a  minor  degree.     He  illustrated 
this  fact  by  experiment,  and  showed  that  these  conditions   are 
necessary  to  the  production  of  contortions   by  lateral  forces.1'* 
The  experiment,  which  may  be  easily  repeated,  merely  consisted 
in  placing  layers  of  various  sorts  of  cloth  upon  a  flat  table,  covering 
them  with  a  loaded  board,  and  applying  lateral  pressure,  so  as  to 
raise  the  superincumbent  weight  to  a  certain  extent,  when  the 
cloth  became  folded  and  contorted  in  a  manner  exactly  analogous 
to  the  contortions  of  natural  rocks. f 

264.  Contorted  strata  are  especially  observable  on  the  flanks  or 
skirts  of  mountain  chains.  The  following  figure  exhibits  a  section 
of  part  of  a  mountain,  in  which  a  stratum  of  limestone,  included 
between  thinner  strata  of  shales  or  slates,  has,  together  with  them, 
been  acted  on  while  in  a  yielding  state,  by  forces  which  have 
caused  deep  and  abrupt  undulations  of  surface.     The  limestone 


stratum,  a,  a,  a,  a,  is  seen  including  in  its  sinuosities,  the  superior 
beds  of  shale,  &c.,  marked  Z>,  6,  6,  and  also  inferior  beds  of  the 
same  nature. 

In  what  regions  of  country  are  contortions  of  strata  most  remarkably 
exhibited  ?  In  what  state  must  the  rocks  have  been  at  the  time  the  con- 
tortions were  produced? 

In  what  manner  may  the  effect  of  contortion  in  strata  be  imitated  ? 

In  what  parts  of  mountain  ranges  are  these  phenomena  particularly  ob- 
servable ? 

*  De  la  Heche's  Geological  Researches,  p.  127. 

t  Transactions  of  the  Royal  Society  of  Edinburgh,  vol.  vii.  p.  85. 


CONFORMABLE  STRATA  387 

265.  In  the  Alps,  between  mount  Righi  and  the  Hospice  of  St. 
Gothard,  a  series  of  mixed  strata  of  limestone,  clay  slates,  shales, 
and  sandstones,  display  such  windings  and  convolutions,  as  might 
have  been  produced  in  the  manner  already  described,  by  the  com- 
bined operation  of  vertical  and  lateral  forces.*     Examples  of  the 
waving  or  zigzag  direction  of  strata  occur  occasionally  in  coal 
mines5-  and  at  Anzin,  near  Valenciennes,  a  remarkable  instance 
has  been  observed  of  this  derangement  of  the  coal  strata,  which 
are  bent  up  and  down,  and  covered  by  horizontal  strata  of  chalk, 
marl,  and  clay,  subsequently  deposited. f 

266.  The  strata,  instead  of  rising  towards  the  summit  of  a  hill, 
may  be  depressed  in  the  centre,  as  if  they  had  been  deposited  in 
a  basin,  or  trough-shaped  hollow. 


The  preceding  figure  represents  a  series  of  strata  thus  arranged, 
each  stratum  having  the  shape  of  a  shallow  inverted  cone  or  dome, 
the  edges  of  which  may  be  traced  all  round  the  mountain.  In  the 
hill  of  St.  Giles,  near  Liege,  this  conformation  of  the  strata  may 
be  noticed  :  sixty-one  beds  of  coal,  alternating  with  rocky  strata, 
form  a  mountain  3200  feet  in  height.  In  South  Wales  and  other 
parts  of  Great  Britain,  the  coal  strata  are  arranged  in  a  similar 
manner. 

267.  When  rocks  belonging  to  different  formations  occur 
together,  one  resting  on  the  other,  that  which  is  placed  underneath 
is  termed  the  fundamental  rock,  and  that  above  it  the  superin- 
cumbent. The  line  where  two  rocks  or  formations  come  in  con- 
tact is  named  either  the  line  of  junction,  being  veiwed  with 
reference  to  the  position  of  the  rocks,  or  the  line  of  separation,  as 
marking  the  distinction  of  their  species.  When  the  strata  of  a 
superimposed  formation  are  parallel  with  those  on  which  they  rest, 
the,  stratification  is  said  to  be  conformable ,-  as  in  the  figure,  p.  385, 
where  the  strata  are  all  horizontal.  Inclined  strata  may  also  be 

What  example  of  contorted  strata  is  found  in  Switzerland  ? 
In  what  manner  are  the  coal  strata  at  Liege  found  to  be  arranged  ? 
What  is  meant  by  the  terms  fundamental  and  superincumbent,  when 
applied  to  rocks  ?     What  is  the  line  of  junction  in  stratifications  ? 

*  De  la  Beche's  Geological  Researches,  p.  129. 

t  For  an  account  of  the  contorted  rocks  along  the  valley  of  the  Juniata, 
oy  Mr.  R.  C.  Taylor,  see  Transactions  of  the  Geol.  Soc.  of  Penn.,  vol.  i.  pp. 
11  and  182.— ED. 


388  GEOLOGY. 

conformable,  the  same  degree  of  inclination  extending  through  all 
of  them. 

263.  If,  on  the  contrary,  the  superimposed  strata  are  horizontal, 
while  the  subjacent  strata  are  more  or  Jess  inclined,  they  are 
relatively  termed  unconformable  strata. 


This  mode  of  superposition  is  shown  in  the  above  diagram,  re- 
presenting a  section  of  a  part  of  a  mountain  composed  of  primitive, 
secondary,  tertiary,  and  alluvial  stratifications.  The  horizontal 
strata,  A,  B,  C,  D,  of  sand,  clay,  shell  limestone,  and  sandstone, 
conformable  among  themselves,  are  seen  reposing  uncomformably 
on  the  highly-inclined  strata  of  slate  and  gneiss,  E,  F,  which  rest 
conformably  on  granite.  The  strata  around  Paris,  consisting  of 
alternate  fresh-water  and  marine  formations,  are  thus  superimposed 
uncomformably  upon  chalk,  which  forms  a  great  basin,  containing 
these  various  deposits,  which  also  cover  its  edges  in  the  less 
elevated  parts,  while  in  some  places  the  chalk  appears  rising 
through  the  upper  strata. 

269.  When  a  series  of  strata  are  nearly  horizontal,  and  extend 
through  a  considerable  tract  of  country,  intersected  by  deep  valleys, 
the  same  strata  will  make  their  appearance  at  nearly  the  same  level, 
in  distant  mountains.     In  the  vicinity  of  Pittsburgh,  in  Pennsyl- 
vania, particularly  along  the  banks  of  the  Monongahela  river,  a 
thick  stratum  of  coal  may  be  traced  through  many  hills  at  the 
same  elevation  above  the  intermediate  valleys.     The  coal  may  be 
worked  by  driving  levels  from  the  sides  of  the  hills,  forming 
open  galleries,  and  thus  obtained  with  little  difficulty.     Owing 
to  the  horizontal  position  of  the  coal,  it  forms  the  bed  of  a  river, 
for  several  miles.* 

270.  When  curved  strata  of  equal  thickness  at  the  top  and  sides 
lie  unconformably  on  other  strata,  the  former  are  said  to  be  saddle- 
shaped;  and  when  such  overlying  strata  gradually  become  thin- 
ner from  the  base  to  the  summit,  thus  wrapping  round  the  sides 
of  the  subjacent  or  fundamental  rock,  they  are  termed  mantle- 
shaped  strata.    Strata  filling  up  a  spheroidal  cavity,  are  denomi- 
nated basin-shaped  ;  and  if  the  cavity  be  oblong,  the  superimposed 
strata  are  styled  trough-shaped. 

To  what  class  of  strata  is  the  term  unconformable  applied  by  geologists  ? 
How  are  these  strata  illustrated  in  the  Paris  basin?     What  are  saddle- 
sJiaped  strata  ?— mantle-shaped  ? — basin-shaped  ? — trough-shaped  ? 

*  See  Am.  Journal  of  Science,  vol.  xxix.,  pp.  58 — 68. 


ANTICLINAL  AXIS.  389 

271.  The  upper  part  of  a  stratum  or  bed,  which,  rising  from 
under  others  makes  its  appearance  at  the  surface,  and  where  it 
consequently  terminates,  is  designated  by  miners  the  outcrop,  or 
basset-edge  of  the  stratum.     Strata  are  said  to  form  outlyers  or  out- 
lying rocks,  when  they  compose  detached  heights,  once  evidently 
continuous  with  extensive  tracts  of  a  similar  geological  struc- 
ture.    Isolated   hills  of  this  kind  are  found  on  the  outskirts  of 
mountain   ranges   or   elevated   plains,  separated  from  them   by 
valleys  of  excavation,  as  in  the  Pittsburgh  coal  strata  above  men- 
tioned. 

272.  Sometimes  the  continuity  of  a  whole  series  of  strata  is 
interrupted,  the  beds  having  been  apparently  broken  through,  and 
shifted  or  heaved  on  one  side  from  their  original  position,  consti- 
tuting  what  is  termed  a  fault,  or  slide.     These  dislocations  of 
strata  are  phenomena  of  an  analogous  nature  to  the  heaving  of 
mineral  veins,  but  they  take  place  on  a  more  extensive  scale.* 

273.  A  dyke  is  a  wall  of  rock  interrupting  the  continuity  of  strata, 
and  filling  up  the  fissures  sometimes  caused  by  faults  or  breaks. 
The  ends  of  the  strata  on  either  side  of  the  fissure  are  occasionally 
tilted  or  bent  upwards,  as  if  the  dyke  had  been  formed  by  the 
protrusion  of  matter  from  below.     Dykes  vary  in  thickness,  from 
a  few  inches  to  many  yards  ;  and  those  which  intersect  coal-beds 
are  composed  of  indurated  clay,  or  more  frequently  of  basalt. 

274.  The  dip,  or  inclination  of  strata,  that  is,  the  point  of  the 
compass  towards  which  they  descend,  is  a  circumstance  deserving 
attention,     [t  has  been  observed,  that  the  dip  is  always  at  right 
angles  to  the  range  or  direction  of  the  strata;  and  that  if  the  dip 
is  given,  the  direction  may  be  inferred,  but  a  knowledge  of  the 
direction  will  not  give  us  the  dip.     The  amount  of  the  dip  of  any 
strata  is  to  be  estimated  by  the  angle  which  they  form  with  the 
horizon ;  and  this  may  be  determined  by  means  of  the  instrument 
called  a  clinometer,  which  is  a  compass  with  an  attached  quadrant. 

275.  An  anticlinal  axis  is  that  line  from  which  the  strata  com- 
posing a  hill  dip  in  opposite  directions.    "  The  ridge  of  a  house- 
top will  convey  an  idea  of  this  line,  and  the  slope  of  the  roof  repre- 
sent the  dip  of  the  strata."f     Some  rocks,  especially  those  of  the 
trap  kind,  as  porphyries  and  syenites,  are  said  to  be  tabular.  Dr. 
Macculloch  terms  the  tables  into  which   these   rocks   may   be 
divided  pseudo-strata.^:  "  The  tabular  structure  consists  of  parallel 
plates  of  rock,  separated  by  regular  seams.     This  structure  has 
been  often  confounded  with  stratification :  it  appears  to  be  the 

What  is  meant  by  the  cropping  out  of  strata  ? 

What  are  outlyers  ?    What  is  a  fault  or  slide  ? 

What  is  a  dyke,  in  geology  ? 

What  is  meant  by  the  dip  of  rock  strata? — How  is  it  ascertained? 

What  is  the  anticlinal  axis  of  a  series  of  strata  ? 

*  For  an  account  of  the  structure,  arrangement,  and  composition  of  me- 
tallic veins,  see  Treatise  on  Metallurgy  and  Mining,  pp.  189 — 192. 
t  De  la  Beche's  Geol.  Man.     Appendix, 
t  Geol.  Classification  of  Rocks,  p.  90. 
2x2 


390 


GEOLOGY. 


result  of  crystallization,  and  is  closely  allied  to  the  columnar 
structure."* 

27(5.  The  only  remaining  description  of  rocks  that  can  be  con- 
sidered as  symmetrical,  with  regard  to  their  external  structure,  are 
those  which  have  been  styled  columnar.  The  most  distinctly 
marked  among-  the  columnar  rocks  is  basalt.  The  columns  they 
exhibit  are  formed  by  the  aggregation  of  prisms  generally  of  a 
pentagonal  figure,  but  they  are  liable  to  desquamation  and  super- 
ficial decomposition,  when  their  angles  become  rounded,  and  their 
forms  variously  modified.  Vast  ranges  of  basaltic  pillars  occur 
in  countries  which  have  been  the  scenes  of  volcanic  action,  as 
the  singular  masses  called  the  Giant's  Causeway,  on  the  northern 
coast  of  Ireland  ;  and  Fingal's  Cave,  in  the  Isle  of  Staffa,  one  of 
the  Scottish  Hebrides.  The  general  appearance  of  extensive 
ranges  of  columnar  rocks  may  be  illustrated  by  the  following 
diagram : 


277.  Beds  of  stratified  rocks,  ff,  a,  «,  are  cut  through  by  a  ba- 
saltic dyke  of  horizontal  prisms,  intersecting  also  ranges  of  verti- 
cal columns,  and  three  large  transverse  dykes  of  amorphous  basalt, 
i,  6,  above  the  highest  of  which  are  detached  masses,  d  and  e,  of 
columnar  basalt.  This  figure  likewise  exhibits  the  interior  struc- 
ture of  prismatic  rocks,  and  the  manner  in  which  the  columns  are 
divided  by  joints.  The  columns  may  not  only  be  vertical  or  hori- 
zontal, as  in  the  foregoing  figure,  but  also  inclined  at  any  given 
angle,  and  sometimes  the  prisms  are  more  or  less  curved,  forming- 
by  their  combinations  rocks  destitute  of  symmetrical  arrangement. 

278.  Rocks  which  are  neither  stratified,  tabular,  nor  columnar, 
can  scarcely  be  said  to  have  any  appropriate  form :  and  we  have, 
therefore  styled  them  amorphous.    They  may  vary  in  dimensions 
as  much  as  in  figure,  and  be  of  any  size,  even  of  mountainous 
bulk.     Thus  granite,  greenstone,  and  some  of  the  trap  rocks  con- 

What  classes  of  rocks  have  no  true  stratification  ? 
What  are  columnar  rocks  ? 

What  remarkable  examples  of  columnar  rocks  are  found  in  the  British 
Islands  ? 

Explain  the  general  appearance  of  stratified  rocks? 

*  Bakewell's  Introd.  to  Geology,  p.  87. 


GRANITIC  ROCKS.  391 

stitute  vast  pillars,  blocks,  and  boulders,  of  every  fantastic  shape. 
Irregular  masses  imbedded  in  other  rocks,  are  styled  nodules. 
They  are  sometimes  rounded,  and  not  unfrequently  flattened  ; 
"  and  in  such  cases,  they  pass  into  the  form  of  non-persistent  and 
extenuated  strata.  Nodules  are  often  imbedded  in  stratified  rocks ; 
but  they  are  also  found  in  granite,  as  is  the  case  with  serpentine. 
The  size  of  these  masses  varies  from  a  foot  to  a  mile  or  more."*  It 
is  difficult  to  determine  how  far  stratification  extends  among  the 
primary  rocks ;  and  even  granite  sometimes  exhibits  traces  of 
what  Dr.  Macculloch  calls  pseudo  strata,  f 

Classification  and  Arrangement  of  Hocks. 

279.  A  cursory  view  of  the  masses  forming  the  crust  of  the  earth 
exhibits  so  much  confusion  and  indefinite  variety  of  composition 
as  must  appear  to  render  nugatory  all  attempts  at  classification ;  and 
hence  it  was  at  one  time  supposed,  that  the  several  formations  were 
destitute  of  all  regularity  in  distribution  and  in  individual  charac- 
ters. The  first  rude  distinction  that  seems  to  have  been  made  was 
that  of  the  German  miners,  who  arranged  strata  of  rocks  in  two 
classes,  namely,  those  containing  metallic  veins,  and  those  which 
were  non-metalliferous.     Lehman,  already  mentioned,  (No.  6,) 
made  the  much  more  important  divisions  of  formations  into  primi- 
tive and  secondary,  or  those  destitute  of  organic  remains,  and  those 
including  such  fossils.      • 

280.  The  celebrated  Werner  modified  and  improved  this  divi- 
sion ;  adding  two  other  classes,  the  transition  and  the  local,  or  as 
they  were  afterwards  called,  tertiary  rocks.  Subsequent  additions 
have  been  proposed  of  alluvial  or  superficial  deposits  ;  and  of  pyro- 
genous  strata,  including  the  trap  and  volcanic  rocks.  These  divisions 
have  been  generally  adopted  by  recent  writers  on  systematic  geo- 
logy ;  though  several  have  thought  fit  to  subdivide  the  secondary 
and  tertiary  rocks  into  distinct  groups  or  formations. 

281.  In  assuming  successions  of  strata  to  a  greater  or  less  ex- 
tent superimposed  around  the  terestrial  globe,  we  must  be  careful 
to  distinguish  what  has  been  inferred  from  limited  observation, 
confirmed,  however,  in  a  certain  measure  by  uncontradicted  expe- 
rience, from  the  deductions  derived  from  appearances  of  an  unequi- 
vocal description.  That  granite,  or  rather  granitic  rocks,  constitute, 
as  elsewhere  stated,  the  basis  or  skeleton  of  the  solid  crust  of  the 
earth,  is  a  conclusion  formed  from  general  observation  that  these 

?,  rocks  where  they  most  extensively  occur  seem  to  rise  from  under 
others  which  are  known  to  occupy  relatively  low  situations,  or  they 

What  is  the  nature  of  amorphous  rocks? 
What  is  meant,  in  geological  language,  by  the  term  nodules  ? 
Who  first  divided  rocks  into  primary  and  secondary  ? 
What  distinctions  were  added  by  Werner? 

*  Dr.  Macculloch's  Geol.  Class,  of  Rocks,  p.  113. 

t  See  p.  328.    On  the  subject  of  stratification  in  general,  see  Greenough's 
Critical  Examination  of  the  First  Principles  of  Geology,  1819,  Essay  I. 
and  Dr.  Boase's  Treatise  on  Primary  Geology. 


392  GEOLOGY. 

form  nearly  vertical  masses  so  included  between  other  rocks  as  to 
indicate  that  the  granite  passes  beneath  those  rocks.  Since,  how- 
ever, the  extent  of  surface  of  granitic  rocks  naturally  or  artifically 
exposed,  is  but  inconsiderable  compared  with  that  of  the  earth's 
surface,  the  notion  that  granite  composes  the  inner  shell  or  lining 
of  the  earth's  crust,  is  at  best  but  a  probable  conjecture. 

282.  Granite,  then,  can  only  be  supposed  to  be  an  universal  for- 
mation ;  and  the  extent  of  many  of  those  above  it  must  at  present 
be  utterly  uncertain.     But  with  respect  to  some  of  the  superior 
strata,  we  know  with  certainty  that  they  are  not  universal  forma- 
tions, and  that  some  cover  only  limited  areas.     Coal  appears  to 
consist  of  circumscribed  beds,  formed  in  basins  or  concavities  of 
older  strata;  the  clays  of  the  London  basin,  and  the  various  de- 
posits  of  the   Paris   basin,   also  compose   circumscribed  beds. 
Chalk,  if  it  deserves  the  character  of  a  general  formation,  (as  it  is 
certainly  a  very  extensive  one,)  is  not  now  universal,  having  been 
removed  apparently  from  some  parts  of  the  surface  of  this  coun- 
try, as  the  weald  of  Sussex,  England,  by  the  violent  action  of  water. 

283.  It  is  only  by  the  gradual  accumulation  of  facts  that  the 
boundaries  of  real  knowledge  can  be  extended.  From  their  situa- 
tion the  more  superficial  rocks  may  be  supposed  to  have  been  the 
most  thoroughly  investigated,  and  since  it  has  been  ascertained 
that  they  include  organic  remains  extremely  singular  and  curious, 
they  have  attracted  particular  attenti§n :  as  the  progress  of  re- 
search proceeds,  however,  it  may  be  expected  that  the  primordial 
or  inferior  rocks  will  also  be  more  closely  examined,  and  that  thus 
various  disputed  points  with  regard  to  them  will  be  satisfactorily 
decided. 

284.  The  manner  in  which  the  several  formations  and  rocks  are 
arranged  so  as  to  form  mountain  masses  may  be  illustrated  by 
the  following  representation  of  a  section  of  the  Brocken  mountain, 
in  the  Hartz  forest  in  Germany. 


Whence  has  it  been  inferred  that  granite  is  the  lowest  of  rocky  strata? 
What  evidence  have  we  that  this  rock  is  universally  extended  beneath 
the  other  strata  ? 

What  example  of  limited  formations  may  be  mentioned  ? 


SUBMEDIAL  ROCKS.  393 

The  perpendicular  mass  in  the  centre,  a,  is  granite,  which  may  be 
supposed  to  extend  laterally  beneath  the  other  rocks  ;  £,  6,  is  clay 
slate,  immediately  enveloping  the  granite ;  c,  c,  is  transition  lime- 
stone ;  rf,  rf,  gray  wacke  slate  ;  e,  e,  old  red  sandstone ;  /,  /,  moun- 
tain limestone,^:,  g,  gypsum ;  A,  A,  variegated  sandstone ;  i, «',  second 
or  newer  gypsum ;  j\  j,  second  limestone  ;  A-,  &,  alluvial  deposits. 
It  may  be  proper  to  observe,  that  this  section  exhibits  only  the  ar- 
rangement and  successive  declination  of  the  rocks  that  Ibrm  the 
Brocken,and  not  their  respective  forms  and  dimensions  ;  and  that 
in  other  mountains  some  of  these  strata  may  be  replaced  by  others, 
or  be  entirely  wanting. 

Synoptical  Arrangement  of  Groups,  Formations,  and  Rocks.* 

285.   I.  Primordial  or  Non-fossilliferous  Rocks. 
A.  Unstratified  rocks. 


Granite,  syenite. 
Greenstone. 
Serpentine. 
Schorl  rock,  &c. 
B.  Stratified  rocks. 
Gneiss. 
Mica  slate. 
Clay  slate. 
Quartz  rock. 


Grampian  hills,  in  Scotland ; 
Cornwall ;  Dofrine  hills,  Nor- 
way; Ural  mountains,  Russia; 
Erzegebirge,  in  Saxony;  Ries- 
engebirge,  in  Silesia  ;  Pyrenean 
mountains ;  eastern  Alps,  from 
St.  Gothard  to  the  plains  of 
Hungary ;  Alleghany  mountains, 
United  States;  Andes,  South 
America. 


Hornblende  slate,  &c. 

286.     II.  Submedial  Rocks. 

(Gray  wacke  Group  of  Lyelt  and  De  la  Beche.    Transition  Rocks  of 
other  Geologists.} 

Sandstone  conglomerate,  slate,  &c. 
Calcareous  flags,  sandstone,  and  schist. 
Shell  limestone,  and  micaceous  sandstone,  &c. 
Coralline  limestone,  and  argillaceous  shale. 
Argillaceous  limestone,  and  sandy  shale. 

Describe  the  several  parts  of  which  the  Brocken  is  composed  ? 
What  individual  strata  compose  the  first  division  of  primordial  rocks? 
What  name  is  given  to  this  division  ? 

What  constitute  the  second  division  of  the  same  class  of  rocks  ? 
In  what  parts  of  the  globe  are  these  rocks  conspicuously  shown? 
What  are  the  five  divisions  of  the  submedial  or  grauwacke  group  ? 

*  This  synoptical  table  is  chiefly  founded  on  "  Table  II.  Showing  the 
Order  of  Superposition,  or  Chronological  Succession  of  the  principal  Sedi- 
mentary Deposits  or  Groups  of  Strata  in  Europe." — Appendix  to  Lyell's 
Prin.  of  GeoL,  vol.  iv.,  with  Additions  and  Modifications,  derived  from  De 
la  Beche's  Geological  Manual ;  Brongniart  Tableau  des  Terrains  qui  com- 
potent  I'Ecorce  du  Globe ;  D'Aubuisson  Traiti  de  Geopnosie,  2nde  edit., 
continuee  par  Amedee  Burat.,  torn.  i.  1834 ;  MantelPs  Geology  of  the 
South-East  of  England,  chap.  ii. ;  and  Outlines  of  the  Geology  of  England 
and  Wales,  by  Conybeare  and  Phillips,  part  i.  Introduction. 


394  GEOLOGY. 

"The  grauwacke  group  occurs  in  Norway,  Sweden,  and 
Russia.  It  forms  a  portion  of  southern  Scotland,  whence  it 
ranges  with  breaks,  as  far  as  regards  the  surface,  formed  by 
newer  deposits  of  the  sea,  down  western  England  and  Wales, 
into  Normandy  and  Brittany.  It  appears  abundantly  in  Ireland. 
A  large  mass  of  it  is  exposed  in  the  district  constituting  the^ 
Ardennes,  the  Eifel,  and  the  Taunus.  Another  mass  forms  a 
large  portion  of  the  Hartz  mountains,  while  smaller  patches 
emerge  in  other  parts  of  Germany,  on  the  north  of  Magdeburg 
and  other  places."— De  la  Beche's  Geol.  Man.,  p.  430.  The 
terms  graywacke  or  transition  are  applied  as  epithets  to  distin- 
guish the  sandstones,  slates,  and  limestones  of  this  group  from 
those  which  occur  in  other  groups.  In  America  the  grauwacke 
is  distributed  over  a  vast  extent  of  country,  from  Alabama  to 
the  Arctic  ocean,  and  is  characterized  by  fossils  which  must 
have  lived  in  a  climate  of  far  higher  temperature  than  exists  at 
present  in  any  regions  without  the  tropics.* 


287.     III.  Medial  Rocks.] 

Carboniferous  group. 

a.  Old  red  sandstone. 

b.  Mountain  limestone. 

c.  Coal  measures,  including  sandstones,  conglomerates, 

clay  with  ironstone,  shales,  and  limestones. 


288.     IV.  Supermedial  Rocks.jf. 

(1.)  Penean,  or  red  sandstone. 
(2.)  Keupric,  or  poecilian. 
'".)  Liasic. 

Oolitic,  or  freestone. 


Wealden. 
Cretaceous. 


289.  Panean  group. 

a.  New   red   sandstone    [Rothliegendes,   Germ.]    \Gres 

Rouge,  Fr.] 

b.  Magnesian  limestone  [Zechsttin,  Germ.] 

In  what  countries  are  the  members  of  this  group  found  ? 
How  extensively  is  it  distributed  on  the  American  continent? 
What  three  individuals  belong  to  the  carboniferous  group  ? 
What  groups  constitute  the  class  of  supermedial  rocks? 
How  many  and  what  individuals  belong  to  the  penean  group  ? 

*  See  Mr.  R.  T.  Conrad's  Paper  on  the  Fossil  Shells  of  the  Grauwacke 
Group,  in  Trans.  Geol.  Soc.  of  Penn.,  vol.  i.  p.  267. — ED. 

t  See  the  following  note. 

t  The  rocks  belonging  to  this  and  the  preceding  order,  (the  medial  and 
supermedial  rocks,  or  those  from  the  old  red  sandstone  to  the  chalk,  inclu- 
sive,) constitute  the  secondary  formations  of  the  Werneriana. 


WEALDEN  GROUP.  395 

290.  Keupric  group. 

a.  Variegated   sandstone,   [Bunter  Sandstein,    Germ.; 

Ores  Bigarre,  Fr.] 

b.  Shell  limestones,  [Muschelkalk,  Germ.] 

c.  Red  or  variegated  marls,   \Keuper,  Germ.]    Marnes 

Irisees,  Fr.J 

291.  Liasic  group. 

a.  Alum  slate,  [Ampelite  alumineux,  Fr.] 

b.  Dark  blue   marl,  with  beds   of  rubbly   limestone — 

sandy  marlstone. 

c.  Blue,  white,  and  yellow  earthy  limestone,  interstratified 

with  clay,  often  slaty  and  bituminous,  [Quadersand- 
stein,  Germ.] 

292.  Oolitic  group. 

a.  Inferior  oolite. 

b.  Great  oolite,  Bath  stone,  Caen  stone. 

c.  Bradford  clay,  [Marne  argilleuse  Jurassique,  Fr.] 

d.  Forest  marble. 

e.  Cornbrash. 

Bradford  clay  and  cornbrash  ought,  perhaps,  to  be 
regarded  as  local  formations,  and  to  be  included  under 
that  of  forest  marble  or  lithographic  slate  ;  with  which, 
where  they  occur,  they  are  associated.  Burat,  indeed 
reckons  Bradford  clay,  forest  marble,  and  cornbrash,  as 
distinct  but  consecutive  members  of  the  oolitic  formation; 
and  Lyell  distinguishes  the  cornbrash  from  the  forest 
marble. 

/.  Oxford  clay — dark  blue,  tenaceous  clay ;  bituminous 
shale,  sandy  limestone,  (Kelloway  rock.) 

g.  Coral  rag,  [Calcaire  Corrallique,  Fr.]  —calcareous, 
shelly,  oolitic  freestone ;  coarse  limestone,  full  of 
corals ;  yellow  sand ;  siliceo-calcareous  grits. 

h.  Kimrneridge  clay,  \_Marne  argilleuse  Havrienne,  Fr.] 

i.  Portland  stone— coarse,  shelly  limestone,  fine-grained 
white*  limestone,  compact  limestone — all  oolitic 
beds  of  chert. 

293.  Wealden  group. 

a.  Purbec   stone — various   kinds   of  limestones,   alter- 

nating with  marls. 

b.  Ashburnham  stpne — bluish-gray  limestone,  alternat- 

ing with  blue  clay,  and  sandstone  shale. 

c.  Hastings  sands  and  clays — fawn-coloured  and  white 
sand,  and  friable  sandstone,  with  clays  and  calcareous 

grits. 

How  many  and  what  individuals  belong  to  the  keupric  ? — the  liasic  ? 
Into  how  many  and  what  subdivisions  is  the  oolitic  group  of  superme- 
dial  rocks  distinguished  ? 
What  ii  dividual  strata  compose  the  wealden  group  ? 


396  GEOLOGY. 

Wealden  group  continued. 

d.  Weald  clay — slaty  clay,  and  limestone,  with  beds 
of  ironstone,  and  Sussex  marble. 

294.  Cretaceous  group. 

a.  Shanklin    sand,    lower  green  sand  \Glaucome  sab- 

leuse,  Fr.] — green,    gray,  white,   and   ferruginous 
sand,  with  clay,  chert,  and  siliceous  limestone. 

b.  Gaut,  or  folkstone  marl — blue  clay,  with  veins  of 

red  ochre. 

c.  Upper  green  sand,  or  firestone  [Glauconie  crayeuse, 

Fr.] — marly  stone,  and  sand  with  green  particles  ; 
layers  of  calcareous  sandstone. 

d.  Chalk,  without  flints. 

e.  Chalk,  with  flints,  or  upper  chalk. 

The  chalk  formations,  d  and  e,  are  very  extensive  in  Eng- 
land, France,  and  other  parts  of  the  continent  of  Europe. 

f.  Maestricht    limestone — soft,   yellowish-white    lime- 

stone, with  siliceous  masses,  resembling  chalk. 

295.    V.  Superior  Rocks. 

(Supra cetaceous,  Tertiary,  or  Newest  Floetz  Rocks  of  different  •Au- 
thors.) 
Lower  formations. 

In  England  (London  basin.) 
a.  Plastic  clay. 
I.  London  clay, 
c.  Bagshot  sand. 
In  France  (Paris  basin.) 

a.  Plastic  Clay. 

b.  Calcaire  grossier. 

396.  Upper  Formations. 

A.  Calcareo-siliceous  strata,  gypsum,  and   marls, 
sand  and  sandstone,  millstone  grft,  and  marls. 

B.  Marine  deposits  of  sand,  forming  the  fahluns 
of  Touraine,  and  of  the  Lower  Loire,  France. 

C.  Subapennine  marl,  subapennine   yellow  sand ; 
English  crag;  and  other  deposits  containing  marine 
fossils. 

D.  Molasse  and  nagelfluhe — accumulations  of  rolled 
pebbles  and  sands,  composed  of  Alpine  detritus. 

E.  Limestone,  sands,  clays,  sandstones,  conglome- 
rates, marls,  with  gypsum;  containing  marine  fossils. 

What  are  the  six  subdivisions  of  the  cretaceous  or  chalk  group  ? 
What  are  considered  in  England  as  constituting  the  lower  formations 
of  the  tertiary  class  ? 

What  distinctions  of  this  class  exist  in  France  ? 

What  five  divisions  are  found  among  the  upper  formations  of  this  class  ? 


VOLCANIC  STRATA.  397 

297.  VI.  Alluvial  Deposits. 

A.  Sand  and  gravel — auriferous  sands,  cascalhao. 

B.  Detritus   of   various   kinds — calcareous   sand- 
stone, with  broken  shells  ;  osseous  breccia. 

C.  Recent  calcareous  formations — coral  reefs  and 
islands,  tufa,  travertin. 

D.  Peat. 

298.  VII.  Volcanic  Strata. 

Ancient — 

Basalt,  trachyte,  greenstone,  &c. 
Recent — 
Lava,  ashes,  moya,  &c. 

What  are  the  four  divisions  of  the  sixth  class  formed  hy  geologists  ? 

How  are  volcanic  strata  divided  ? 

What  particular  substances  belong  to  each  division? 


Works  in  the  Department  of  Geology. 

BakewelPs  Introduction  to  Geology  with  an  outline  of  Profes- 
sor Sillirnan's  course  of  lectures  on  the  same  subject.  1  vol.  8vo. 

De  la  Beche's  Geological  Manual.   1  vol.  8vo.  Philadelphia. 

Lyell's  Principles  of  Geology.  3  vols.  8vo. 

Ure's  New  System  of  Geology.  London.  1829. 

Maclure's  Geology  of  the  United  States,  with  a  map. 

Featherstonhaugh's  Geological  Report  to  Congress.  1835. 

Professor  Rogers's  Report  on  the  Geology  of  North  America, 
in  the  Transactions  of  the  British  Association  at  Edinburgh. 

American  Journal  of  Science,  various  numbers,  particularly 
volumes  xxii.  and  xxix.,  the  latter  of  which  contains  a  highly 
important  account  of  the  geological  character  of  the  great  coal 
deposits  of  the  valley  of  the  Ohio,  and  its  tributaries,  by  Dr. 
Hildreth. 

Transactions  of  the  Geological  Society  of  Pennsylvania,  vol.  i. 


Hitchcock's  Report  of  the  Geology  of  Massachusetts.  1  vol. 
8vo.  1833. 

Transactions  of  the  Geological  Society  of  London.  5  vols.  4to. 

Mantell's  Geology  of  the  South-East  of  England.    1  vol.   4to. 

Journal  of  the  Acadamy  of  Natural   Sciences.    7  vols.  8vo., 
hitherto  published. 

2L 


ORYCTOLOGY. 

1.  THE  term  Oryctology*  has  been  employed  to  denote  the  na- 
tural history  of  minerals  and  fossils,  with  special  reference  to  the 
situations  they  are  found  to  occupy  within  or  upon  the  crust  of 
the  earth.    Mineral  and  fossil  are  words  of  analogous  signification, 
implying  bodies  that  have  been  obtained  by  mining  or  excavation; 
but  the  former  is  now  usually  appropriated  to  those  bodies  which  are 
mere  chemical  compounds,  exhibiting  no  traces  of  organization;  and 
the  latter  to  such  as  retain  in  any  degree  the  form  and  appearance 
of  animal  and  vegetable  substances,  however  changed  or  modified  as 
to  their  composition.     These  bodies  might  be  generally  designated 
metamorphosed  organic  remains,  were  they  not  sometimes  pre- 
sented to  us  by  nature  absolutely  unaltered,  as  in  the  very  remark- 
able instance  of  the  fossil  elephant,  found  embalmed  in  ice,  in 
Siberia,  in  the  beginning  of  the  present  century. 

2.  From  the  structure  and  composition  of  animal  and  vegetable 
substances,  however,  it  necessarily  follows,  that  but  very  few 
comparatively  can  occur  in  such  a  state  of  complete  preservation. 
Trees  are  sometimes  found  buried  in  bogs  and  mosses,  standing 
erect,  with  their  roots  and  branches  very  little  altered.    The  more 
dense  and  compact  parts  of  organized  beings  are  most  frequently 
preserved,  while  the  softer  substances  which  entered  into  their 
composition   have   been   destroyed    or  removed.      Hence  whole 
skeletons,  or  detached  bones,  and  shells,  either  entire  or  broken, 
are  among  the  most  common  fossilized  organic  remains.     They 
occur,  however,  under  variously  modified  conditions  :  some  having 
undergone  little  change  of  substance,  as  those  masses  of  shells 


To  what  does  the  term  oryctology  apply  ?  What  remarkable  instance 
can  be  mentioned  of  a  specimen  of  extinct  animals  found  entire  ?  What 
vegetable  fossils  are  sometimes  discovered  in  their  natural  positions? 
What  parts  of  organized  beings  are  commonly  wanting  in  fossil  specimens? 
How  is  this  exemplified  in  carbonate  of  lime  ? 

*  From  the  Greek  'Opuxrdj./ossi'Z,  and  Aoyoj,  a  discourse. 

398 


ENCRIMTES.  399 

and  corals,  which  being  conglutinated  by  carbonate  of  lime,  form 
blocks  or  beds  of  variegated  marble* 

The  preceding  figure  represents  the  surface  of  a  slab  of  Kil- 
kenny marble,  inlaid  with  shells  and  coralloids,  which  have  a  very 
pleasing  effect ;  and  many  of  which  are  so  perfect,  that  their  forms 
may  be  traced,  and  their  species  distinguished. 

3.  The  Sussex  or  Petworth  marble  is  another  kind  of  shell 
limestone,  which  affords  beautifully-veined  sections,  and  has  been 
used  for  ornamental  purposes.    It  is  found  in  layers  varying  from 
a  few  inches  to  a  foot  or  more  in  thickness,  in  the  weald  clay,  in 
the  south-eastern  part  of  England.    "  This  limestone  is  of  various 
shades  of  bluish-gray,  mottled  with  green  and  ochraceous  yellow, 
and  is  composed  of  the  remains  of  fresh-water  univalves,  formed 
by  a  calcareous  cement  into  a  beautiful  compact  marble.    It  bears 
a  high  polish,  and  is  elegantly  marked  by  the  sections  of  the  shells 
which  it  contains  :  their  constituent  substance  is  a  white  crystallized 
carbonate  of  lime,  and  their  cavities  are  commonly  filled  with  the 
same  substance,  presenting  a  striking  contrast  to  the  dark  ground 
of  the  marble.     In  other  varieties,  the  substance  of  the  shells  is 
black,  and  their  sections  appear  on  the  surface  in  the  form  of 
numerous  lines  and  spiral  figures.      Occasionally  a  few  bivalves 
(cyclas}  occur,  and  the  remains  of  the  minute  crustaceous  coverings 
of  the  cypris  faba  very  constantly."*    This  limestone  is  durable; 
"yet  from  long  exposure  in  damp  situations,  it  undergoes  decom- 
position, and  the  petrified  testacea  may  then  be  extricated  almost 
entire."f 

4.  The  mountain  limestone,  called  by  Mr.  Bakewell,  "  upper 
transition  limestone,"   "  is  one  of  the  most  important  calcareous 
rocks  both  from  its  extent,  the  thickness  and  number  of  its  beds, 
the  quantity  and  variety  of  its  organic  remains,  and  its  richness 
in  metallic  ores,  particularly  of  lead.     In  Derbyshire,  where  the 
different  beds  of  limestone  have  been  pierced  through  by  the  mi- 
ners, the  average  thickness  of  the  three  uppermost  is  about  160 
yards:  the  beds  are  separated  by  beds  of  trap  or  basalt,  resem- 
bling ancient  lavas.     The  lowest  limestone  has  not  been  pierced 
through." 

5.  "  The  prevailing  characteristic  organic  fossils  are  encrinites 
and   madrepores.     The   upper  beds    of  mountain   limestone,   in 
Derbyshire,  appear  to  be  almost  entirely  composed  of  encrinites."^: 
Polished  slabs  of  entrochai  or  encrinital  marble  are  sometimes 

What  is  the  substance  which  has  replaced  animal  matter  in  the  fossa 
shells  in  marble  ? 

Which  appears  to  be  the  more  durable — the  testaceous  fossils,  or  their 
interposed  cement  ? 

What  is  mountain  limestone  in  geological  nomenclature  ? 

What  are  its  prevailing  fossils  ? 

*  Mantell's  Geology  of  the  South-East  of  England,  p.  184. 

t  Idem,  p.  186. 

}  Bake  well's  Introduction  to  Geology,  p.  131. 


400  ORYCTOLOGY. 

employed  for  tables  and  other  ornamental  furniture.   A  portion  of 
such  a  table  is  exhibited  in  the  following  figure. 


The  table,  from  which  the  above  was  taken,  is  of  a  lig-ht  gray 
colour,  variegated  with  white ;  but  the  mountain  limestone  has  oc- 
casionally a  black,  and  sometimes  a  reddish-brown  ground,  or  is 
veined  or  clouded. 

6.  Beds  of  black  marble,  with  madrepores,  are  found  in  various 
parts  of  England  and  Wales.     The  black  tint  of  this  marble  is 
owing  to  the  presence  of  bitumen:  it  is  otherwise  generally  com- 
posed of  nearly  pure  carbonate  of  lime,  except  some  beds,  which 
consist  partly  of  carbonate  of  magnesia. 

7.  Sometimes  the  organic  remains  are  found  to  have  undergone 
considerable  modification  as  to  their  composition,  while  their  forms 
exist  unaltered.  Thus  vegetable  bodies  are  changed  into  ochraceous 
earth  or  tuff,  like  the  umber  found  in  the  environs  of  Cologne.  Wood 
impregnated  with  silex  is  not  unfrequently  met  with  in  various 
parts  of  the  world  ;  but  the  finest  specimens  are  said  to  be  obtained 
from  the  vicinity  of  Schemnitz  and  at  Telkobanya,  in  Hungary. 
It  also  occurs  in  the  diluvian  detritus,  in  the  green  sand  of  the  cre- 
taceous group,  and  in  the  Portland  stone.     The  texture  of  wood 
may  be  traced  in  some  siliceous  minerals,  as  jasper,  agate,  cal- 
cedony,  opal,   and    pitchstone,  betraying   their  ultimate   origin. 
Argillaceous  earth   may  cause  the  mineralization  of  wood ;  and 
different  parts  of  vegetables  are  often  imbedded  in  the  rocks  com- 
posed of  this  earth.     Iron  in  the  state  of  sulphuret,  or  in  that  of 
carbonate,  may  pervade  the  substance  of  vegetable  fossils.     "  In- 
numerable   seeds,  seed-vessels,  &c.,  have   been   found,  by  Mr. 
Crow  and  others,  in  the  blue  clay  of  Sheppey,  in  the  state  of 
pyrites.    Most  of  these  belong  to  plants  unknown  to  our  bota- 

For  what  purposes  in  the  arts  is  this  marble  employed  ? 
To  what  does  black  marble  owe  its  colour? 
To  what  changes  arc  fossils  found  to  have  been  subjected  ? 
In  what  situations  is  wood  found  to  be  replaced  by  silex  ? 
Jn  what  state  may  iron  exist  in  the  forms  of  vegetable  fossils? 


BOVEY  COAL.  401 

nists ;  the  existing  plants  to  which  the  others  seem  to  approximate 
are  some  of  those  of  the  warmer  climates."* 

8.  Wood  is  occasionally  impregnated  with  pyritical  or  carbonated 
copper,  the  latter  forming  very  beautiful  fossils,  the  finest  speci- 
mens of  which  (consisting  of  charred  wood,  marked  with  the  most 
vivid  blue,  and  green  tints,  with  patches  of  the  carbonate  in  the 
state  of  malachite)  are  obtained  from  the  copper  mines  of  Siberia.f 
Volkmann  and  other  authors  have  mentioned  fossil   wood   im- 
pregnated with  silver ;  but  its  occurrence  is  somewhat  questiona- 
ble.}:    Specimens  of  wood  thoroughly  impregnated  with  galena 
(sulphuret  of  lead)  have  been  found  in  Derbyshire. § 

9.  As  might  be   expected    from   their   original   composition, 
vegetable  fossils  are  often  found  to  have  undergone  changes  which 
have  reduced  them  nearly  to  the  state  of  carbonaceous  or  bituminous 
minerals.   Schookius  relates,  that  masses  of  bitumen  are  frequently 
found  among  peat ;  and  sometimes  resembling,  in  size  and  figure, 
walnuts,  eggs,  and  pine-nuts.||     Wood  is  also  found  in  the  state 
of  jet,  lignite,  and  Bovey  coal.  This  last  mentioned  fossil,  which 
occurs  in  several  successive  strata  at  Bovey,  near  Chudleigh,  in 
Devonshire,  extending  for  some  miles,  has  been  worked  for  more 
than  a  century,  being  used  for  fuel  in  burning  lime  and  for  other 
purposes. 


10.  The  preceding  figure  represents  a  fragment  of  Bovey  coal. 
"This  variety  is  evidently  a  dicotyledonous  or  gymnospermous 
phanerogamic  plant,  for  it  presents  all  the  external  characters  of 

In  what  states  may  copper  be  found  in  the  forms  of  vegetable  fossils  ? — 
Lead  ?  What  constituents  of  vegetables  are  most  frequently  found  in  de- 
posits of  ancient  timber  ? 

*  Parkinson's  Outlines  of  Oryctology :  an  Introduction  to  the  Study  of 
Organic  Remains.  2d  edit.  1833.  p.  27. 

t  See  Parkinson's  Organic  Remains  of  a  Former  World.  2d  edit.  1833 
vol.  i.  pp.  388,  389.  {  Idem,  p.  390. 

§  See  Martin's  Outlines  of  an  Attempt  to  establish  a  Knowledge  of  Ex- 
traneous Fossils  on  Scientific  Principles,  p.  150. 

li  Parkinson's  Organic  Remains,  vol.  i.  p.  208. 


402  ORYCTOLOGY. 

stems  belonging  to  that  class."*  Here  the  trails  of  the  woody 
tissue  are  very  distinct,  and  the  structure  but  little  altered.  This 
fossil  is  only  found  in  the  superior  strata ;  but  the  remains  of 
vegetables  are  likewise  abundant,  as  might  be  anticipated,  in  the 
coal  formation,  where  however  they  occur,  in  general,  more  entirely 
metamorphosed.  The  annexed  figure  is  a  representaton  of  a  stro- 
bilus  or  cone  of  a  pine,  (Pinus  antiqua,}  which  has  been  completely 
carbonized. 


1 1 .  The  transformation  in  some  cases  is  so  complete,  that  though 
the  forms  and  even  the  colours  may  be  preserved,  all  the  elements 
of   an    organized  being  have  been    removed  by  the  mysterious 
operations  of  nature.    Such  bodies  are  mere  casts  of  the  originals, 
and  it  not  unfrequently  happens  that  branches  of  trees,  or  some 
other  parts  of  vegetables,  or  those  of  animals,  having  been  inclosed 
in  stony  matter,  the  original  substance  has  disappeared,  but  on 
dividing  the  lapidescent  table,  the  impression  of  the  organized 
bodies  will  be  found  on  one  layer,  and  casts  in  relief  on  the  other. 

12.  In  general  the  inferior  surface  of  leaves  is  displayed  in 
relief,  and  the  superior  is  indented.     The  small  veins  and  hairs 
that  mark  these  surfaces  are  occasionally  preserved  in  perfection, 
apparently,  while  not  a  particle  of  animal  or  vegetable  matter  re- 
mains in  the  stone,  the  whole  having  been  volatilized.   The  follow- 
ing figure  exhibits,  a  mould  or  impression  of  a  branch  of  a  tree, 

For  what  purposes  is  the  mineralized  wood,  termed  Bovey  coal,  applied  ? 

What  class  of  vegetables  must  have  entered  into  the  composition  of  that 
stratum  of  fossils?  Why  is  it  more  important  to  study  the  internal  struc- 
ture of  fossil  vegetables  than  of  those  which  are  recent? 

In  what  manner  may  we  obtain  correct  ideas  of  the  forms  of  vegetables, 
when  the  original  matter  has  entirely  disappeared  ? 

Which  surface  of  a  leaf  appears  to  have  resisted  most  effectually  the 
compressing  effect  of  the  strata  in  which  it  has  been  imbedded  ? 

*  The  Internal  Structure  of  Fossil  Vegetables  found  in  the  Carbonife- 
rous and  Oolitic  Deposits  of  Great  Britain,  described  and  illustrated.  By 
Henry  T.  M.  Witham,  of  Lartington,  F.  G.  S ,  F.  R.  S.  E,  &c.  Edinburg, 
1833.  4to.  p.  50.  To  the  finely-executed  plates  which  accompany  this 
work,  we  are  indebted  for  the  figure  in  the  text,  and  for  those  of  some 
of  the  vegetable  fossils  represented  in  the  following  pages.  Mr.  Witham 
has  contributed  much,  by  his  skilfully  conducted  researches,  towards  ob- 
taining an  accurate  knowledge  of  the  internal  structure  of  fossilized  stems 
of  plants;  and  by  an  improved  method  of  cutting  and  polishing  those 
bodies,  so  as  to  adapt  them  for  microscopical  examination,  he  has  been  en- 
abled to  elucidate  their  intimate  organization,  and  thus  to  afford  the  most 
essential  means  for  ascertaining  their  relative  affinities  with  the  genera 
and  species  of  existing  vegetables :  a  circumstance  obviously  of  the  highest 
importance  with  regard  to  the  bodies  of  which  the  more  characteristic 
portions,  the  ibliage  and  organs  of  fructification,  have  very  rarely  escaped 
destruction. 


FOSSIL  ZED  PLANTS. 


403 


with  leaves  resembling  the  fir  or  yew,  on  shale,  or  limestone  ;  on 
the  margin  of  the  mass  are  traces  of  some  other  vegetable,  probably 
a  fern. 


i 


13.  Among  the  fossilized  remains  of  vegetable  foliage,  the  most 
abundant,  especially  in  the  shales  and  argillaceous  schists  above 
the  coal,  are  those  which  belonged  to  different  kinds  of  ferns.     It 
is,  however,  very  difficult  to  identify  them  with  living  species. 
Dr.  Woodward  states,  that  out  of  one  hundred  and  thirty-eight 
specimens  which  he  submitted  to  the  examination  of  four  eminent 
botanists,  they  were  able  to  point  out  only  eleven  which  bore  a 
decided  resemblance  to  those  now  existing,  and  twenty-three  were 
totally  unlike  any  English  plant.* 

14.  Mr.  Parkinson  laid  some  fossilized  ferns,  of  which  he  has 
given  figures,  before  Sir  James  E.  Smith,  who  observed,  that 
"these  fossil  remains  of  vegetables  are  a  sort  of  botanical  riddles  ; 
and  with  respect  to  those  which  appear  to  be  ferns,  the  difficulty 
of  determining  to  what  species  the  several  representations  may  be 
referred,  is  augmented  by  their  being  so  many  things  which  they 
nearly  resemble,  without  being  the  same."     He  spoke  doubtfully 
of  almost  all  of  them,  but  conjectured  that  they  were  all  foreign, 
and  productions  of  a  warm  climate.f     The  annexed  figure  repre- 
sents the  impression  of  a  branch  of  fern,  and  others  will  be  given 
in  a  subsequent  page. 


What  class  of  vegetable  remains  is  found  most  abundant  in  shales  and 
clay  slates  ?  What  difficulty  opposes  their  acccurate  determination  ? 

What  change  of  climate  appears  to  have  taken  place  in  the  temperate 
zones  since  those  vegetables  were  produced  ? 

*  Dr.  Woodward's  Natural  History  of  English  and  Foreign  Fossils,  1729. 
vol.  i. ;  Catalogue  of  English  Fossils,  part  ii.  p.  9. 
t  Parkinson's  Organic  Remains,  vol.  i.  pp.  416,  417. 


404 


ORYCTOLOGY. 


15.  Mr.  Parkinson  questions  the  existence  of  antholithes,  or  fos- 
sil flowers,  or  at  least  asserts  that  it  is  merely  conjectural.  He 
says:  "The  tender  and  almost  succulent  substance  of  the  petals, 
stamina,  and  pistilla,  will  furnish  very  little  reason  for  supposing 
that  they  should  resist  a  destructive  resolution,  sufficiently  long 
to  allow  them  to  pass  through  those  chemical  changes,  by 
which  such  duration  would  be  given  to  their  original  forms,  as 
would  secure  their  passing  unchanged  in  their  figure  from  the 
vegetable  to  the  mineral  kingdom." 

16.  The  existence  of  impressions  of  flowers 
in  the  fossil  state,  has  been  fully  established 
by  their  presence  in  specimens  where  they 
are  clearly  developed.  Floral  forms  may  thus 
be  exhibited,  so  that  their  resemblance  to 
those  of  recent  plants  may  sometimes  be 
traced,  as  in  the  marginal  figure,  which  re- 
presents a  mould  or  impression  of  a  radiated 
or  stellated  blossom,  apparently  of  a  syngene- 
sious  plant,  like  the  marigold  or  China  aster. 

17.  It  is  certain  that  "  the  earlier  writers  on  this  science  too 
frequently  admitted  resembla'nces,  when  the  connexion  between  the 
supposed  model  and  the  archetype  were  too  equivocal  to  authorize 
them.     Thus  Mylius  imagined  that  he  traced  the  flower  of  the 

mouse-ear  on  a  flint,  and  the  rose  of 
Jericho  on  a  schist,  from  Manebach, 
both  of  which  M.  Walch  believes 
were  in  reality  merely  impressions 
of  troehites."*  Fanciful  as  the 
analogies  undoubtedly  were  by 
which  some  authors  have  been  led 
_  to  describe  certain  fossils  as  antho- 
lithes,  there  can  be  no  doubt  but 
flowers  as  well  as  leaves,  have 
sometimes  been  imbedded  in  rocks 
in  such  a  manner  that  their  forms 
have  been  more  or  less  preserved, 
furnishing  casts  or  impressions. 
The  annexed  figure  exhibits  a 
beautiful  impression  on  sandstone 
of  a  branch  of  a  tree,  with  long 
lanceolate  leaves  and  blossoms,  or 
rudiments  of  blossoms. 

18.  In  the  case  of  shells,  corals,  or  other  bodies  included  in  lime- 
Why  cannot  the  parts  of  fructification  be  resorted  to  for  determining  fos- 
sil plants  ? 

Have  we  no  example  of  the  preservation  of  those  parts  ? 

What  errors  on  this  subject  were  committed  by  the  earlier  writers? 


Parkinson'*  Organic  Remains,  vol.  i.  p.  437. 


GEOLOGICAL  ARRANGEMENT  OF  MINERALS,  &C.          405 

stone  and  sandstone  rocks,  the  whole  organic  substance  may  be 
dissolved  and  canied  away,  leaving  a  cavity  in  the  rock  bearing 
the  impression  of  the  foreign  body,  and  in  this  cavity  is  a  mould 
or  cast  of  the  interior.  Thus  the  screwstones,  as  they  are  called, 
have  been  cast  or  moulded  in  the  cavities  of  crinoidal  columns. 
"The  most  extreme  case  of  mineralization  or  petrifaction  is  pro- 
duced by  a  process  in  addition  to  that  just  described,  when  the 
cavity  left  by  the  removal  of  the  shell  or  coral  is  again  filled  up 
by  crystals  of  calcareous  spar,  deposited  by  water  filtrating 
through  the  stone.  Sometimes  only  a  few  crystals  connect  the 
inner  mould  or  cast  to  the  exterior  impression,  but  generally  the 
whole  cavity  is  filled  by  the  spar,  which  thus  represents  truly 
the  shape  of  the  original  body,  but  displays  no  trace  whatever  of 
its  internal  texture."* 

19.  With  respect  to  the  changes  that  organized  bodies  undergo, 
they  must  be  influenced  considerably  by  the  nature  of  the  con- 
taining rock.     "  In  the  green  sand  almost  all  the  shells  are  sili- 
cified  ;  in  the  oolitic  rocks  many  are  changed  to  calcareous  spar ;  in 
the  clays  very  slight  changes  have  happened  to  any  of  the  organic 
remains.     On  the  other  hand,  the  original  nature  of  the  organic 
substance  has  very  much  influenced  its  mode   of  conservation. 
Echinital  and  crinoidal  remains  are  almost  invariably  converted 
to  a  peculiar  kind  of  opaque  calcareous  spar,  in  whatever  strata 
they  occur  :  gryphaeae  and  astreeee  retain  their  laminae ;  inocerami 
and  belemnites  their  fibres. 

20.  As  to  vertebrated  animals,  "  their  soft  portions  have  perished, 
but  their  teeth,  bones,  and  scales  remain,  either  connected  or  sepa- 
rated in  consequence  of  the  decay  of  the  ligaments,  cartilages,  &c. 
The  hardening  ingredient  of  bones  is  principally  phosphate  of  lime, 
that  of  teeth  is  a  mixture  of  phosphate  and  carbonate  of  lime. 
It  is  generally   the   fact  that   their   gelatinous   or  membranous 
portion  has  been  diminished,  and  their  earthy  admixture  increased, 
by  the  subterranean  chemistry  to  which  they  have  been  subjected, 
and,  in  consequence,  their  specific  gravity  is  much  augmented."f 

Geological  Arrangement  of  Minerals  and  Fossils. 

21.  There  are  two  modes  of  formation  to  which  the  origin  of  the 
rocks  composing  the  crust  of  the  earth  might  be  ascribed.  "The  first 
consists  in  the  more  or  less  rapid  consolidation  of  masses  which 
had  been  previously  in  a  dissolved  state ;  and  the  second  in  the  gra- 

How  are  screwstones  produced  ? 

On  what  circumstance  does  the  degree  of  change  from  a  recent  speci- 
men to  its  fossilized  state  mainly  depend  ? 

What  is  the  mineral  which  replaces  organized  matter  in  the  green 
sand  formation  ? 

*  EncyelopJEd.  Metropol. — Treatise  on  Geology,  vol.  iv.  p.  548. 
t  Idem. 


406  ORYCTOLOGT. 

dual  deposition  of  solid  matter  from  a  fluid  with  which  it  had  been 
mechanically  or  chemically  combined.  Vast  fields  of  ice,  and 
beds  of  lava,  are  occasionally  or  periodically  formed  at  present,  by 
the  more  sudden  process  of  solidification  ;  and  layers  of  silt  and 
sand,  and  beds  of  travertin  limestone,  are  produced  by  the  slower 
method  of  precipitation.  The  inferior  unstratified,  as  well  as  the 
trap  rocks,  are  usually  considered  as  being,  like  those  of  volcanic 
origin,  the  results  of  igneous  fusion  and  congelation.  But  all  the 
stratified  rocks  are  regarded  as  aqueous  deposits,  and  these,  which 
are  by  far  the  most  numerous,  must  have  owed  their  existence  to 
the  protracted  operations  of  nature. 

22.  The  stratified  rocks,  from  the  graywacke  series  to  the  ter- 
tiary and  alluvial  formations,  include  a  multitude  of  distinct  de- 
posits, most  of  which  inclose  organic  remains  derived  from  suc- 
cessive races  of  animals  and  vegetables,  comparatively  few  of 
which,  except  in  the  upper  formations,  seem  to  have  any  living 
congeners,  but  on  the  contrary,  many  of  these  relics  present  us 
with  the  forms  of  strange  beings  that  once  peopled  the  earth,  and 
which  have  ceased  to  exist  for  countless  ages  past.     Rocks  ar- 
ranged in  strata,  one  above  another,  may,  by  their  peculiarities  of 
structure  and  contents,  afford  the  means  for  ascertaining  their  re- 
lative age,  or  rather  order  of  formation. 

23.  "  Geognostic  epochs,"  says  Brongniart,  "are  very  different 
from  chronological  epochs :  the  latter  are  determined  by  the  suc- 
cession of  time,  but  not  so  the  former,  which  are  founded  on  the 
grand  phenomena  or  catastrophies  that  limit  a  geognostic  period. 
By  this  term  we  designate  the  whole  time  during  which  the  same 
geognostic  phenomena  have  taken  place  on  the  surface  of  the  earth. 
These  periods  may  amount  to  numerous  ages,  or  to  only  a  few 
years:  thus  the  space   of  time   during  which   the   granite  dis- 
played itself  over  all  parts  of  the  surface  of  the  globe,  accompanied 
by  the  minerals  which  it  contains,  forms  a  remarkable  geognostic 
period.     That  in  the  course  of  which  the  trilobites  existed,  with 
their    contemporary  organized    beings,  whilst    the    argillaceous 
schists  and  the  carboniferous  and  bituminous  limestones  were  depo- 
sited, was  another  geognostic  period,  of  which  the  average  duration 
of  the  life  of  a  trilobite,  and  the  number  of  the  generations,  if  it  were 
possible  to  discover  them,  might  loosely  indicate  the  duration. 

24.  We  have  another  remarkable  example  of  a  geognostic  period 
in  the  state  of  repose  which  seems  to  have  prevailed  in  the  crust 
of  the  earth,  since  the  existing  continents  have   received   their 
forms  and  limits,  the  sea  assumed  its  level,  and  the  atmosphere 
its  temperature;  since  the  animals  and  vegetables  that  inhabit  the 

In  what  two  modes  may  the  strata  of  the  earth's  crust  have  been  formed  ? 

What  is  generally  supposed  to  be  the  origin  of  granite,  gneiss,  and  trap 
rocks  ? 

What  striking  trait  distinguishes  the  fossil  animals  in  the  lowest  beds 
in  which  their  remains  are  found  ? 

How  are  geological  ages  or  periods  to  be  distinguished  from  chronolo- 
gical periods  ? 


INFERIOR  ROCKS.  407 

sea,  or  live  on  the  surface  of  the  earth,  have  varied  but  little  from 
what  they  are  at  present ;  this  state  of  repose,  established  by  all 
observations,  all  historical  traditions,  constitutes  the  last  geognos- 
tic  period,  the  commencement  of  which  must  be  dated  at  least 
four  thousand  years  ago,  and  which  may  extend  for  a  long  series 
of  ages  to  come. 

25.  "  As  we  are  ignorant  whether  the  arrangement  of  the  dif- 
ferent groups  is  similar  over  the  whole  globe,  it  is  impossible  to 
determine  whether  the   geognostic  periods    have  been  of  equal 
extent,  and  also  contemporaneous  over  the  surface  of  the  earth. 
For  instance,  whether  since  the  ammonites  and   the  belemnites 
have  ceased  to  live,  and  the  chalk  to  appear  in  Europe,  in  order 
to  be  succeeded  by  the  cerites  and  the  tertiary  deposits,  the  first 
mentioned  cephalopodous  molluscs  have  not  continued  to  exist, 
and  the  chalk  to  be  deposited  in  India  and  in  America.* 

26.  From  the  preceding  observations,  it  must  be  concluded 
that  though  certain  European  groups  or  formations  may  be  charac- 
terized by  the  presence  of  particular  fossils,  the  same  formations 
may  occur  in  other  quarters  of  the  world  unaccompanied  by  such 
fossils,  or  the  fossils  may  be  found  in  rocks  differing  in  mineralo- 
gical  composition  from  those  in  which  they  appear  in  Europe. 
It  is,  however,  a  point  of  importance  to  be  enabled  to  discriminate, 
by  reference  to  their  contents,  the  rocks  of  a  single  continent,  or 
even  those  of  any  one  country ;  and  thus  far,  at  least,  it  may  be 
admitted  that  geognostic  oryctology  has  advanced. f 

Primordial  or  Inferior  Hocks. 

27.  These  rocks  are  negatively  characterized  by  the  absence 
of  any  organic  remains,  or  conglomerated  fragments  of  transported 
matter;   whence  it  may  be  inferred  that,  however  they  might 
have  been  produced,  they  underwent  the  process  of  consolidation 
in  a  short  space  of  time ;  unlike  the  sedimentary  rocks,  which  were 
formed  by  gradual  and  successive  deposition.    It  is  also  supposed, 
that  since  there  are  no  relics  of  animals  or  vegetables  in  the  strati- 
fied inferior  rocks,  their  formation  must  have  preceded  the  existence 
of  organized  beings  on  the  surface  of  the  earth. 

28.  The  inferior  rocks,  (including  in  that  appellation  the  gray- 
How  might  we  calculate  the  duration  of  the  period  in  which  carboni- 

ferdus  limestone  was  formed  ? 

What  extent  of  observations  would  be  necessary  in  order  to  determine 
the  relative  duration  of  geognostic  periods? 

What  classes  of  rocks  are  wholly  destitute  of  organic  remains? 

What  may  we  infer  respecting  the  time  at  which  animals  first  existed, 
compared  with  that  at  which  primitive  strata  were  at  the  surface  of  the 
globe  ? 

'  Tableau  des  Terrains  qui  composent  1'Ecorce  du  Globe.  Introd.  pp.  8, 9. 
t  The  observation  of  strata  and  the  examination  of  fossils  prove  that 
every  European  group  has  its  equivalent  in  America. — EJ>. 


408  ORYCTOLOGY. 

M| 

wacke  formations,  from  which  some  of  the  lower  rocks  can  scarcely 
be  distinguished)  are  the  grand  repositories  of  mineral  bodies. 
Among  them  are  found  the  metals  and  metallic  ores,  the  gems, 
and  other  rare  and  curious  mineral  compounds.  These,  indeed,  oc- 
casionally occur  in  the  ascending  strata  ;  but  it  will  in  general  be 
evident  that  such  minerals  have  been  detached  from  their  ori- 
ginal situations,  and  dispersed  by  some  convulsions  of  nature ;  as 
is  the  case  with  diamonds,  which  are  found  enveloped  in  the 
cascalhao,  a  comparatively  recent  deposit  in  Brazil ;  with  the  gold 
dust  obtained  from  fluviatile  sands,  and  the  stream-tin  of  Corn- 
wall. 

29.  Some  metals,  as  tin,  tungsten,  and  molybdena,  are  almost 
exclusively  the  produce  of  the  primordial  rocks,  or  are  imme- 
diately derived  from  them ;  and  gold,  silver,  lead,  copper,  iron, 
cobalt,  zinc,  manganese,  arsenic,  and  mercury,  are   abundantly 
disseminated  through  rocks  of  this  class,  in  veins,  beds,  strings, 
or  detached  nodules ;    and  many  primitive  districts  are  charac- 
terized by  the  metalliferous  deposits  they  contain.    "Nothing  can 
be  more   beautiful  than  the  dru&y  cavities  met  with  in  primitive 
mountains,  whose  walls  are  lined  with  pure  and  variously  tinted 
and  crystallized  topaz,  beryl,  rock  crystal,  fluor  spar,  and  calcareous 
spar;  the  gneiss,  granite,  and  mica  slate,with  their  imbedded  crystals 
grains  of  sapphire,   chrysolite,   and    garnet;    and  the   veins   in 
granite,  clay  slate,  and  other  primitive  rocks,  with  their  emeralds, 
axinites  and  spinel  rubies,  afford  to  the  mineralogist  highly  inte- 
resting combinations."* 

30.  Observations  on  the  deposition  of  silica  from  the  water  of 
hot  springs,  together  with  the  supposed  impossibility  of  forming 
some  mineral  compounds  by  fire,  induced  the  geologists  of  the 
school  of  Werner  to  ascribe  the  production  of  granitic  rocks  to 
water.     But  the  discoveries  of  Sir  James  Hall  and  Mr.  Gregory 
Watt,  relative  to  the  effect  of  gradual  cooling  on  carbonate  of 
lime  and  other  bodies  fused  by  heat,  causing  them  to  assume  a 
crystalline  structure,  invalidated  the  arguments  derived  from  the 
second  consideration;  and  subsequent  researches  afford  abundant 
evidence  of  the  igneous  origin  of  granitic  rocks  and  their  included 
minerals. 

31.  Mitscherlich  found  that  the  slags  from  iron  smelting-fur- 
naces  are  often  crystallized,  have  the  form  of  augite,  and  agree 
with  it  in  chemical  composition.    He,  also,  by  exposing  to  intense 
heat  the  substances  of  which  certain  minerals  consist,  obtained 
crystals  of  those  minerals;  thus  producing,  artificially,  amphibole, 
mica,  and  hyacinth.  Berthier,  likewise,  formed  silicates  of  manga- 
nese, as  well  as  of  iron,  in  his  furnaces,  and  obtained  them  regularly 

In  what  rocks  are  the  mineral  repositories  chiefly  found  ? 
Why  was  the  origin  of  the  primitive  rocks  referred,  by  the  German 
geologists,  to  aqueous  deposits? 

*  Encyclopaedia  of  Geography,  pt.  ii.  book  ii.  p.  220. 


SUBMEDIAL  ROCKS.  409 

crystallized.*  Admitting1,  then,  that  granitic  rocks  and  those 
with  which  they  are  more-  directly  associated  were  formed  by 
consolidation,  after  having  been  fused  by  heat,  it  must  be  manifest 
that  if  shells  or  other  parts  of  living  beings  had  entered  into 
their  composition,  no  traces  of  them  would  have  remained,  since,  as 
to  structure,  at  least,  they  must  have  undergone  utter  destruction. 
The  primordial  rocks,  therefore,  may  be  regarded  as  being  dis- 
tinguished by  the  absence  of  organic  remains  and  being  the 
chief  repositories  of  minerals. 

Submedial  Rocks. 

32.  With  respect  to  these  rocks  and  the  higher  strata,  our  space 
will  admit  of  only  a  few  notices  of  the  characteristic  fossils  of  the 
several  rocks  or  formations,  with  descriptions  of  some  of  the 
more  curious  and  important. 

The  submedial  or  transition  rocks  are  not  unfrequently  so  inter- 
mixed with  the  stratified  primordial  rocks,  that  it  is  difficult  to 
discover  the  distinction  between  them.f  Viewed  on  the  large 
scale,  they  consist  of  "a  stratified  mass  of  arenaceous  and  slaty 
rocks,  intermingled  with  patches  of  limestone,  which  are  often 
continuous  for  considerable  distances.  The  arenaceous  and  slate 
beds,  considered  generally,  bear  evident  marks  of  mechanical 
origin,  but  that  of  the  included  limestones  may  be  more  question- 
able."^: 

By  what  experiments  was  its  igneous  origin  rendered  probable  ? 
What  materials,  found  in  other  formations,  are  wholly  wanting  in  the 
primordial  rocks  ? 

What  must  have  been  the  origin  of  beds  of  sand  and  slate  ? 

*  See  Johnston  on  Chemistry,  in  Rep.  of  Brit.  Assoc.  1832,  p.  486  ;  Cuvier 
Discours  sur  les  Progres  recens  de  la  Chimie,  pronounce  en  Mai,  182'5, 
dans  une  Seance  des  Quatre  Academies;  and  Annales  des  Mines. 

t  This  difficulty  is  fully  admitted  by  one  of  the  latest  writers  6n  system- 
atic geognosy.  "Some  of  the  rocks  constituting  the  primitive  group  are 
continued,  and  still  more  developed  in  the  transition  group;  as  the  argil- 
laceous schists  and  calcareous  rocks;  and  others,  as  the  quartz  and  tho 
graywacke,  are  intimately  connected  with  the  primitive  quartz  and  schists ; 
so  that  it  might  be  supposed,  that,  from  the  lowest  granites  to  the  upper 
transition  rocks,  there  was  only  one  grand  period." — Trail '&  de  Geoynosie  ; 
mis  en  Rapport  avec  VInlrod.,  pub.  en  1828,  par  M.  D'Anfiuisson  de,  Voisins. 
Pqr  Amedie  BuraL  1834.  torn,  i.,  p.  209.  Hence  M.  Bnrat  proposes  a 
division  of  the  transition  rocks  into  two  parts  or  classes.  Mr.  De  la  Beche 
remarks,  that  "towards  the  lower  part  of  the  grauwacke  groupe  its  fossili- 
ferous  character  disappears,  and  the  presence  of  crystalline  rocks,  appa- 
rently of  contemporaneous  origin,  becomes  more  common.  This  change 
varies  much  in  different  countries  ;  but  in  general  the  slaty  rocks  gradually 
prevail,  presenting  a  very  great  thickness  of  argillaceous  schists.  We 
seem  to  have  arrived,  in  the  descending  order,  at  a  state  of  the  world 
when  there  was  a  combination  of  those  causes  which  have  produced  fos 
siliferous  and  non-fbssiliferous  rocks." — Geol.  Man.,  p.  422. 

\  De  la  Beche's  Geol.  Man.  p.  414. 
2M 


410  ORYCTOLOGY. 

33.  It  is  in  the  calcareous  rocks  of  this  class  chiefly  that  orga- 
nic remains  are  found ;  for  the  gray  wacke  sandstones  appear  to 
contain  none,  and  the  transition  slates  relatively  few.    The  vege- 
table fossils  found  in  these  rocks  are  seldom  in  such  a  state  as  to 
afford  traces  of  their  analogies  with  those  of  living  plants.  So  far 
as  can  be  determined  from  those  which  have  been  made  out,  it 
appears   that   the   same   kind   of  vegetation  probably  prevailed 
during  the  period  in  which  these  formations  took  place,  as  during 
the  depositions  of  the  carboniferous  rocks. 

34.  As  to  the  animal  fossils,  they  are  generally  derived  from 
the  lower  orders  of  beings,  consisting  principally  of  zoophytes, 
radiated  animals,  conchifers,  molluscs,  and  crustaceous  animals. 
A  few  ichthyolites  have  been  found,  indicating  the  existence  of  at 
least  one  genus,  and  two  or  three  species  of  fishes.     These  rocks 
contain  a  mixture  of  genera  of  animals  inhabiting  the  seas  and 
oceans  of  the  present  day,  and  of  others  which  are  now  not  known ; 
but  the  species  have  all  become  extinct. 

35.  Among  the  more  remarkable  animal 
fossils  are  the  trilobites,  (see  marginal  figure,) 
long  known  in  England  under  the  appellation 
of  "  Dudley  fossils,"  from  their  frequent  oc- 
currence in  the  Dudley  limestone.  They  are 
found  so  abundantly  in  the  mountain  lime- 
stone, in  different  parts  of  England,  as  to  be 
characteristic  of  that  formation.  Specimens 
have  also  been  discovered  in  Germany 
Sweden,  and  America.  Another  kind  of 
trilobite  (Asaphus  debuchii}  is  so  abundant  in 
some  parts  of  Wales,  that  the  laminae  slates 
are  charged  with  them,  and  millions  probably 
lived  and  died  not  far  from  the  places  where  we  now  discover 
their  remains.  A  great  number  of  species  of  these  fossils  are 
found  in  the  limestone  beds  at  Trenton  falls,  New  York,  and 
other  parts  of  the  United  States.*  A  variety  of  conjectures  have 
been  hazarded  with  regard  to  these  extinct  animals,f  which  ap- 
pear to  have  been  Crustacea. 


What  is  the  character  of  the  fossils  found  in  transition  limestone? 

What  orders  of  animals  appear  to  have  existed  at  the  time  the  transition 
rocks  were  formed  ? 

How  are  the  fossil  fishes  of  the  transition  group  characterized,  compared 
with  recent  genera  and  species? 

What  class  of  fossils  is  found  particularly  abundant  in  the  old  transition 
limestone  ? 


*  See  Dr.  Jacob  Green's  Monograph  of  American  Trilobites  Also,  the 
Transactions  of  the  Geological  Society  of  Pennsylvania,  for  a  Description 
of  some  non-descript  Trilobites,  by  Dr.  Harlan. — ED. 

t  See  Parkinson's  Organic  Remains,  vol.  iii.  pp.  271.  275. 


PENTREMITES.  411 


36.  The  crinoid  animals  constituted  a  once  numerous  class  ot 
zoophytes,  some  genera  and  species  of  which  have  continued  up 
to  the  present  day  ;  while  others,  which  are  found  in  various  rocks, 
have  disappeared  from  among  living  animals.     The  lily  encrinite 
(see  preceding  figure)  belongs  to  the  mountain  limestone,  and  its 
remains  form  extensive  strata  of  that  rock,  of  which  a  representa- 
tion has  been  given  in  a  preceding  page. 

37.  In  Lower  Saxony  and  Westphalia,  also,  this  stone  is  so 
abundant  as  to  be  used  for  building;  and  is  composed,  like  the 
Derbyshire  marble,  chiefly  of  entrochal  columns  or  stems  of  the 
encrinite  ;  but  specimens  of  the  body  are  very  rare.  These  animals 
were  composed  of  a  multitude  of  small  bones,  forming  a  vertebral 
column,  probably  attached  at  its  basis  to  the  surface  of  rocks, 
and  surmounted   by  a  cup,  from   the  edge  of  which  proceeded 
digitated  processes,  the  removal  of  the  outer  portions  of  which,  in 
the  preceding  figure,  shows  the  cluster  of  tentacula  by  which  they 
were  terminated.     The  whole  skeleton  must  have  been  involved 
in  a  thick  fleshy  covering. 

Another  highly  interesting  genus  of  fossils  found  in  the  transi- 
tion series,  particularly  the  upper  beds  of  that  formation,  is  the 
pentremites,*  first  discovered  and  named  by  the  late  distinguished 
naturalist,  Thomas  Say,  Esq.  It  is  of  a  radiating  or  star-shaped 
figure,  and  appears  to'have  been  fixed  by  the  centre  to  an  articu- 
lated column. 

In  what  rocks  are  crinoid  fossils  discovered  ? 

In  what  manner  were  the  encrinites  constituted  ? 


*  See  the  Paper  of  Mr,  Troost,  in  the  Trans,  of  the  Geol.  Soc.  of  Penn. 
vol.  i.  p.  224. 


412 


ORYCTOLOGY 


38.  Among  the  corals  are  found  some  genera 
of  which  there  are  existing  species.  The 
annexed  figure  represents  a  madreporite.  "  It 
appears  to  have  been  imbedded  in  a  hard, 
close-grained  limestone,  of  a  pale  yellowish 
colour,  part  of  which,  containing  fragments 
of  shells  and  other  marine  remains,  still  ad- 
heres to  the  madreporite.  The  madreporite 
itself  is  formed  of  a  spathose  substance 
strongly  impregnated  with  iron  ;  as  is  the 
case  with  all  the  fossil  madrepores  found  at 
Steeple  Ashton,  the  locality  of  this  fossil."* 
39.  Notwithstanding  there  is  a  relatively 
small  proportion  of  organic  remains  in  the 
submedial  rocks,  it  is  evident  that  they  must 
have  been  deposited  when  the  atmosphere 
was  adapted  to  the  vegetation  of  plants,  and 
when  the  sea  was  capable  of  affording  habita- 
tion arid  food  for  various  kinds  of  animals ; 
and  though  no  remains  of  terrestrial  animals 
have  been  preserved,  it  is  at  least  probable  that  such  existed,  for 
whom  the  vegetables  served  as  food.  Of  the  marine  animals,  vast 
multitudes  have  utterly  perished,  without  leaving  any  traces  be- 
hind. "  Mere  fleshy  creatures  may  have  existed  in  myriads, 
without  any  of  them  having  been  transmitted  to  us.  In  proof  of 
this,  if  any  were  requisite,  we  may  inquire  what  portion  of  those 
myriads  of  fleshy  animals  which  now  swarm  in  some  seas,  (as  the 
medusae,)  could  be  transmitted  as  organic  remains  to  future 
ages."t 

Medial  Rocks. 

40.  The  formations  of  this  class,  constituting  the  "medial 
order"  of  Conybeare,  are  included  among  the  floetz  or  flat  rocks 
of  Werner,  and"  by  other  geologists  have  been  regarded  as  forming 
the  lowest  group  of  secondary  rocks.  They  comprehend  the 
principal  deposits  of  coal,  or  great  coal-fields;  and  hence  the  term 
carboniferous  has  been  generally  applied  to  them.  The  lowest  of 
these  rocks,  termed  the  old  red  sandstone,  contains  but  few  or- 
ganic remains  ;  and  so  far  as  they  have  been  observed,  they  ap- 

To  what  great  division  of  fossils  docs  the  madreporite  belong? 

What  must  have  been  the  condition  of  the  atmosphere  when  the  sub- 
medial  rocks  were  forni.,J  ? 

What  classes  of  anime'.s  have  left  no  fossil  remains? 

By  what  different  na^v-s  have  the  medial  rocks  been  designated  ? 

Which  is  the  lowest  of  this  group  of  formations? 

What  term  has  been  applied  to  the  rocks  of  this  class  in  consequence  of 
their  containing  coal  ? 

What  organic  remains  are  found  in  carboniferous  sandstone? 

*  Parkinson's  Organic  Remains,  vol.  ii.  p.  67. 
t  De  la  Beche's  Geol.  Man.,  p.  429. 


FORMATION  OF  COAL.  413 

pear  to  be  of  a  similar  character  with  those  in  the  strata  im- 
mediately below  or  next  above  this  sandstone. 

41.  The  mountain  limestone,  also  termed  carboniferous  lime- 
stone, presents  considerable  analogies  with  the  transition  lime- 
stone, relics  of  corals  and  radiated  animals  being  inclosed  in  it, 
especially  those  of  the  encrinites.     It  is  usually  of  a  gray  colour, 
and  granular,  but   sometimes  of  a  foliated  texture,  particularly 
where  it  comes,  in  contact  with  trap  rocks.  Some  varieties  are  im- 
pregnated with  bituminous  or  carbonaceous  matter,  and  are  of  a 
black  colour,  as  the  marble  called  lucullite.     Lead  ore,  and  occa- 
sionally the  ores  of  zinc  and  copper,  occur  in  this  rock,  which  has 
therefore  been  called  metalliferous  limestone.     It  seems  to  be  the 
most  recent  formation  in  which  metals  are  found  in  veins,  which 
seldom  rise  into  the  coal  strata;  and  when  they  do  they  soon  ter- 
minate. 

42.  The  coal-measures,  as  they  are  technically  termed,  including 
the  associated  beds  of  shale,  clay,  and  ironstone,  compose  the 
highest  formation  of  medial  rocks ;   though  they  are  not  exclu- 
sively confined  to  this  series.*  This  valuable  mineral  is  generally 
deposited  in  basin  or  trough-shaped  hollows,  of  various   extent, 
from  one  to  many  miles ;  and  it  sometimes  covers  large  areas, 
which  may  at  a  distant  period  have  been  deltas  over  which  great 
rivers  dispersed  immense  piles  of  vegetable  matter,  such  as  are 
now  collecting  at  the  mouth  of  the  Mississippi.     The  manner  in 
which  coal  and  the  alternating  strata  are  usually  disposed  has  been 
described  already,  and  illustrated  by  a  section  of  the  coal-basin  in 
the  hill  of  St.  Giles,  near  Liege. f  In  the  great  coal-field  of  South 
Wales  the  strata  are  arranged  in  a  vast  trough,  over  a  tract  nearly 
100  miles  in  length,  and  from  5  to  20  in  breadth.     It  contains 
twenty-three    beds   of    workable    coal,    the   thickest   nine    feet 
deep  ;  and  in  some  parts  there  are   sixteen  seams  or  layers  of 
ironstone.^: 

The  coal  fields  of  the  United  States  extend  through  large 
portions  of  Pennsylvania,  Ohio,  Maryland,  Virginia,  Kentucky, 
Tennessee,  Indiana,  Illinois,  Missouri,  Alabama,  and  Arkansas,  to 
points  within  500  miles  of  the  Rocky  mountains. 

43.  Dr.  Hutton  ascribed  the  formation  of  coal  to  accumulations 

What  ones  in  mountain  limestone  ? 
What  are  the  chief  varieties  of  this  limestone  ? 
Which  is  the  highest  formation  of  medial  rocks  ? 
In  what  manner  are  coal  measures  usually  arranged  ? 
What  examples  of  accumulating  vegetable  matter  may  illustrate  the 
probable  mode  of  deposition  in  the  coal  beds  ? 

*  "  Le  carbone  n'appartient  pas  exclusivement  au  terrain  houiller.  Nous 
avons  vu  former  des  amas  et  des  couches  exploitables  dans  le  terrain  de 
transition,  et  il  se  presentera  encore  dans  des  formations  posterieures  ;  mais 
il  y  atteint  son  maximum  d'abondance,  et  devient  un  caractere  presque 
constant." — Burat  TraM  de  Geognosie,  torn.  i.  p.  274. 

t  See  387. 

t  Bake  well's  Introd.  to  Geol.,  p.  152. 

2  M2 


414  ORYCTOLOGY. 

of  carbonaceous  matter,  from  various  sources,  at  the  bottom  of  the 
sea ;  but  geologists  at  present  seem  to  be  generally  disposed  to 
regard  this  mineral  as  a  deposit  from  fresh-water,  consisting  prin- 
cipally of  vegetables,  which  became  submerged  in  lakes,  some- 
times occupying  the  spot  on  which  they  had  grown,  and  into  which 
descending  torrents  washed  the  clays  and  sands  forming  the  beds 
interposed  between  the  several  strata  of  coal.  These  depositories, 
however,  must  have  been  occasionally  overflowed  by  the  sea ;  for 
in  some  instances,  beds  of  marine  shells  are  found  between  those 
of  coal. 

44.  That  the  coal  strata  have  been  partly  formed  by  plants 
growing  on  the  spot  appears  from  the  repeated  examples  which 
have  been  adduced  of  stems  of  trees  found  in   coal  mines,  in  a 
vertical  position  with  their  roots  imbedded  in  the  strata  below. 
Mr.  Witham  mentions  the  occurrence  of  such  stems  in  the  Der- 
went  mine,  near  Blanchford,  Durham  ;  and  of  numbers  of  fossil 
vegetables,  chiefly  si.gi llarise,  erect,  with  their  roots  imbedded  in 
a  small  seam  of  coal  under  trie  sandstone,  and  all  truncated  on  the 
line  of  the  high  main  coal  bed,  to  the  formation  of  which  the  tops 
probably  contributed.*   A  curious  instance  of  similar  appearances 
is  noticed  by  Mr.  Wood,  as  having  been  observed  at  Killingworth 
colliery,  in   the  same  district.      There  were   many  fossil    trees 
rising  perpendicularly  10  feet  through  various  strata  of  shale  and 
sandstone.     They  were  filled  with  sand,  resembling  that  of  the 
upper  beds  ;  so  that  they  must  have  been  hollow  when  those  beds 
were  deposited. f 

45.  Mr.  Witham,  in  a  subsequent  publication  to  that  just  quoted, 
has  given  an  account  of  some  interesting  researches  concerning 
the  structure  of  fossil  plants  found  in  the  carboniferous  strata. 

In  the  neighbourhood  of  Coldstream,  on  the  banks  of  the 
Tweed,  numerous  fossil  vegetables  occur  imbedded  in  shale,  be- 
longing to  the  carboniferous  group.  Stems  of  trees  are  found 
contorted  and  flattened,  as  if  they  had  been  subjected  to  extreme 
pressure.  The  longest  stem  obtained  was  not  much  more  than  4 
feet,  and  the  lowest  part  of  it  about  6  feet  in  circumference. 

46.  "  In  1820  an  enormous  trunk  was  exposed  in  the  lowest 
bed  of  Craigleith  quarry,  near  Edinburgh,  at  the  depth  of  up- 
wards of  130  feet.     The  length  of  this  trunk  was  36  feet,  and  its 
diameter  at  the  base  3  feet.    It  lay  in  a  nearly  horizontal  position, 
corresponding  with  that  of  the  stratum  of  hard  white  sandstone  in 
which  it  was  imbedded.     It  was  incased  in  a  layer  of  coaly  mat- 

What  account  did  Hutton  give  of  these  beds  ? 
How  do  modern  geologists  regard  them  ? 

What  facts  prove  that  the  vegetables   contributing   to  the  coal  beds 
sometimes  grew  on  the  spots  where  they  now  repose  ? 
Into  what  form  is  the  cross  section  of  imbedded  trees  found  to  be  changed? 

*  Observations  on  Fossil  Vegetables.  1831.  p.  7. 

t  De  la  Beche,  from  Trans,  of  Society  of  Natural  History  of  Newcastle, 
vol.  j. ;  and  Lindley  and  Hutton's  Fossil  Flora  of  Great  Britain. 


FOSSIL  STEMS  OF  TREES. 


415 


ter,  being  probably  the  altered  remains  of  the  bark."  From 
analysis  it  was  found  to  be  composed  of  carbonate  of  lime,  60 
parts;  oxide  of  iron,  18;  alumine,  10;  and  carbonaceous  matter, 
9.  Its  interior  structure  resembled  that  of  the  coniferae. 

47.  "  In  November,  1830,  a  magnificent  fossil  stem  was  dis- 
covered in  tbe  same  quarry,  which,  in  geological  position,  is 
situated  in  the  mountain  limestone  group,  and  lies  considerably 
below  the  great  coal  basins  of  the  Lothians." 


•It. 


48.  "The  length  of  the  stem,  (see  preceding  figure,)  from  the 
base  to  the  top,  was  47  ft.  It  presented  the  appearance  of  a  large 
branchless  trunk,  in  some  parts  greatly  flattened,  so  as  to  form  an 
elliptical  section."  Dimensions:  A,  diameter,  5  ft.  by  2  ft.;  B, 
C,  2  ft.  8  in.  by  1  ft.  5  in. ;  D,  E,  2  ft.  7  in.  by  1  ft. ;  F,  1  ft.  10  in. 

What  was  the  composition  of  the  fossil  tree  found  at  Craigleith  quarry? 


416  ORYCTOLOGY. 

by  1  ft.  3  in. ;  G,  1  ft.  7  in.  by  1  ft.  4  in. ;  H,  supposed  prolonga- 
tion of  the  top  of  the  stem,  12  ft. ;  I,  upper  part  of  the  tree  first 
discovered,  showing  a  cavity,  the  seat  of  a  branch.  The  superin- 
cumbent mass  must  have  been  above  100  feet  in  depth.  The  bark 
was  converted  into  coal.  This  fossil  also  exhibits  the  usual  struc- 
ture of  the  coniferae,  and  appears  from  analysis  to  have  consisted 
of  carb.  of  lime,  62;  carb.  of  iron,  33;  carbon,  5.  :  sp.  gr.,  2.87. 

49.  A  third  fossil  stem  of  a  similar  character  was  found  in  1831, 
in  the  same  quarry.* 

Messrs.  Lindley  and  Hutton,  in  their  "  Fossil  Flora,"  vol.  i.  p. 
9,  pi.  ii.,  have  described  the  trunk  of  1826  and  that  of  1830,  under 
the  appellation  of  Pinites  withami  ,•  ard_  have  named  that  of  1831, 
Pinites  medullaris. 


Some  remarkable  vegetable  fossils  have  been  obtained  from  the 
Northumbrian  coal  mines  ;  one  of  which  is  shown  in  the  preceding 
figure. 

The  specimens  "  consist  of  sub-cylindrical  or%  slightly-com- 
pressed dichotomous  stems.  The  surface  is  covered  by  a  thick 
envelope  of  carbonaceous  matter,  presenting  indistinct  protube- 
rances arranged  in  spiral  series,  and  beneath  which  are  observed 
papillae  of  an  elliptical  form,  higher  than  broad.  The  above  figure 
represents  a  portion  of  one  of  the  stems,  denuded  of  its  carbona- 
ceous covering."]- 

What  were  the  dimensions  of  the  largest  specimen  found  at  the  same 
place  ?  How  many  per  cent,  of  carbon  were  found  in  its  composition  ? 

What  is  the  exterior  appearance  of  the  fossil  stems  found  at  the 
Northumbrian  coal  mines. 

*  Witham's  Illustrations  of  Fossil  Vegetables,  sect.  iii. 
t  Witham's  Illustrations,  p.  52. 


STRUCTURE  OF  RECENT  LYCOPODIUM. 


417 


50.  The  marginal  figure  exhibits  a 
longitudinal  section  of  a  part  of  one 
of  These  fossils,  in  which  the  central 
axis  or  pith  is  entirely  filled  by  cal- 
careous spar,  and  a  tube  of  carbona- 
ceous matter.  From  the  axis  emanate, 
on  all  sides,  cylindrical  processes, 
consisting  of  cellular  tissue,  with 
central  fasciculi  of  vessels.  They  proceed  obliquely  upwards  and 
outwards,  and  terminate  in  the  papillary  eminence  on  the  surface 
of  the  stem.* 


51.  These  processes  are  seen  cut  obliquely  in  the  foregoing 
figure,  representing  a  transverse  section  of  the  stem,  the  processes 
appearing  as  white  oblong  markings  dispersed  in  the  brown  pa- 
renchymatous  tissue. f  The  planfr  evidently  belongs  to  the  vas- 
cular cryptogamic  class,  and  appears  to  be  allied  to  the  lycopodia. 


What  materials  are  found  in  the  interior  of  the  mass  ? 

To  what  class  of  vegetables  have  those  stems  been  supposed  to  belong  ? 

Why? 


Witham's  Illustrations,  p.  52. 


t  Idem,  r».  53. 


418 


ORYCTOLOGY. 


52.  The  preceding  figure  represents  a  tranverse  section  of  the 
Lycopodium  clavatum,  exhibiting  the  same  kind  of  cellular  struc- 
ture and  central  axis,  as  appears  in  the  fossil  stem. 


An  oblique  section  of  a  process  of  the  Lycopodium  clavatum,  showing 
the  structure  of  the  tissue,  of  which  there  are  traces  in  the  fossil.* 

53.  To  the  plant  which  produced  the  Northumbrian  fossils,  Mr. 
Witham  has  assigned  the  name  of  Lepidodendron  harcourtii.     He 
has  examined  and  described  the  structure  of  fossil  plants  belong- 
ing to  four  distinct  genera  :  Pinites,  pitus,  anabathra,  and  lepi- 
dodendron  ;  including  nine  species.     From  the  sections  of  fossil 
stems  found  in  the  coal  strata  and  mountain  limestone,  he  infers 
that  "  these  combustible  beds  were  masses  of  vascular  and  cel- 
lular cryptogamic   plants,  mixed  with    gymnospermous   phane- 
rogamic trees,  or  others  of  a  closely-allied  structure ;"  and  not 
entirely  of  vascular  cryptogamic  vegetables,  as  some  have  sup- 
posed.f 

54.  Branches  and  leaves  of  plants,  especially  of  ferns,  are  abun- 
dant in  the  coal-measures  and  the  formations  with  which  they  are 
connected.     Numerous  specimens  are  preserved  in  various  cabi- 
nets of  natural  history ;  two  of  which  are  exhibited  in  the  follow- 
ing figures. 


What  appellation  has  been  applied  to  the  fossil  form  of  the  Northum- 
brian locality  ?  What  mixture  of  plants  was  probably  once  found  in  the 
region  to  which  they  belonged  ? 

What  classes  of  plants  are  particularly  abundant  in  coal  beds  ? 

*  Besides  the  preceding,  Mr.  Witham  bas  given  several  other  interesting 
magnified  sections  of  different  parts  of  these  fossils, 
t  Illustrations,  sect.  i.  p.  10. 


LIAS  AND  OOLITE.  419 

Super-medial  Rocks. 

55.  The  penean  or  lower  group  of  these  rocks  consists  partly 
of  new  red  sandstone,  with  beds  of  marl,  and  also  gypsum  and 
rock  salt ;  and  in  the  bituminous  copper  slates  are  found  the  first 
traces  of  those  immense  reptiles  of  the  lizard  family,  which  are 
so  abundant  intheliasic  group.  The  zechstein  or  magnesian  lime- 
stone contains  only  a  few  genera  of  plants,  several  of  shells,  mol- 
lusca,  radiaria,  and  zoophytes,  three  of  fishes,  and  one  reptile. 

56.  In  the  keupric  group  occurs  a  greater  variety  of  plants  and 
animals,  including  among  the  latter  five  or  six  genera  of  saurian  rep- 
tiles. Among  the  organic  remains  of  the  muschelkalk,  two  of  the 
most  characteristic  are  perhaps  the  Ammonites  nodosus,  and  the 
Encrinites  moniliformis,  or  lily  encrinite ;  but  the  former  is  also 
found  in  the  higher,  and  the  latter  in  the  inferior  rocks.  Among  the 
red  marls  and  sandstones  by  which  the  shell  limestone  is  some- 
times replaced,  are  likewise  beds  of  rock  salt;  and  from  the  pre- 
sence of  that  useful  mineral  in  this  and  the  preceding  group,  they 
have  been  described  together  by  some  geologists,  under  the  appel- 
lation of  the  "  Saliferous  System."* 

57.  The  formations*  which  constitute  the  two  following  groups, 
(the  liasic  and  the  oolitic,)  are  peculiary  rich  in  fossil  remains. 
Among  those  of  vegetable  origin  are  lignites,  fossil  wood,  some- 
times siliceous  impressions  and  casts  of  fern,  (see  p.  403,)  cyca- 
daceae,  and  fuci.   But  these  are  not  the  only  kinds  of  plants.  Mr. 
Wit-ham  found  in  these  groups  three  species  of  a  genus  named 
pence,  peculiar  to  the  lias  and  oolite,  or  at  least  not  occuring  in 
anterior  deposits ;  and  two  species  of  pitus,  which  also  appear  in 
the  mountain  limestone.  From  an  examination  of  these  fossil  trees, 
he  asertained  that  their  tissue,  in  tranverse  sections,  corresponds 
precisely  with  that  of  our  coniferae,  and  more  especially  with  that 
of  the  genus  pinus. 

58.  From  the  circumstance  that  the  concentric  layers  or  the  fos- 
sil vegetables,  which  Mr.  Witham  has  described  as  occuring  in 
the  lias  and  oolite  of  England  being  like  those  of  recent  trees, 
some   much   broader   than   others,   he   infers,    that   the   climate 
which  existed   at  the   epochs  when  these  vegetables  grew,  re- 
sembled that   of  the   same  country  at  the  present  day,  in  the 
irregularity  of  its  successive  summers.     "  The  coniferae  of  the 
coal  formation  and  mountain  limestone  group  have  few  and  slight 
appearances  of  the  lines  by  which  the  annual  layers  are  separated  ; 
which  is  also  frequently  the  case  with  the  trees  of  our  present 

What  constitute  the  lower  part  of  the  supermedial  rocks  ? 
What  animals  are  found  in  the  lower  members  of  this  series  of  rocks  ? 
What  class  of  rocks  constitute  the  saliferous  system  ? 
What  vegetable  organic  remains  are  found  among  the  lias  and  the  ooli- 
tic group  ? 
To  what  classes  do  the  fossil  trees  of  this  group  belong  ? 

*  See  Encyclopaedia  Metrop. — Mixed  Sciences,  vol.  iv.  p.  608. 


420 


ORYCTOLOGY. 


tropical  regions.  It  is  therefore  possible,  that  at  the  epochs  of  these 
formations,  the  changes  of  season,  as  to  temperature,  at  least, 
were  not  abrupt."*  Hence  it  may  be  concluded,  that  the  climate 
of  these  latitudes,  which  resembled  that  of  tropical  countries  when 
the  vegetables  forming  the  coal  strata  flourished,  had  become 
more  temperate  and  variable  during  the  growth  of  the  plants  im- 
bedded in  the  liasic  formations. 

59.  But  the  groups  now  under  consideration  are  most  remarka- 
ble on  account  of  their  animal  fossils,  which  are  numerous  and 
interesting.  In  the  lias  the  crinoid  radiaria  again  make  their  ap- 
pearance. 


The  Briarean  pentacrinite  is  one  of  those  animals  the  remains 
of  which  are  most  common  in  England.  The  preceding  figure 
exhibits  part  of  the  vertebral  column,  and  articulated  processes 
connected  with  it.  These  fossilized  animals  were  akin  to  the 
encrinites,  from  which  they  are  characteristically  distinguished 
by  the  shape  of  the  bones  composing  the  spinal  columns.  In  the 
encrinites  they  are  circular  disks,  as  may  be  perceived  by  turning 
to  the  figure,  p.  411,  in  which  several  of  these  bones  are  shown 
imbedded  in  mountain  limestone.  The  bones  of  the  pentacrinite 

What  inference  has  been  drawn  from  an  inspection  of  foesil  vegetables  ? 

What  changes  of  climate,  in  the  temperate  zones,  appears  to  have  taken 
place  during  the  period  from  the  deposition  of  the  coal  strata  to  that  of  the 
lias  groups  ? 

For  what  class  of  fossils  are  these  groups  most  remarkable  ? 

*  Illustrations  of  Fossil  Vegetables,  p.  58. 


ICHTHYOSAURUS. 


421 


are  pentangular.  Multitudes  of  them  are  found  detached  in  the 
formations  of  the  liasic  and  oolitic  groups,  and  in  the  higher 
strata;  from  their  figure  they  have  been 
named  astroites  or  star-stones ;  and  they 
are  so  often  met  with  at  Lassington  hill, 
near  Gloucester,  England,  that  they  have 
obtained  the  provincial  appellation  of  "  Las- 
sington stones." 

60.  The  pentacrinite  is  one  of  those  fos- 
sil animals,  of  which  there  are  probably  liv- 
ing analogues.    The  marginal  figure  repre- 
sents the  upper  portion  of  a  radiated  animal, 
described  by  M.  Guettard,  from  a  specimen 
obtained  at  Martinique.*      A  pentacrinus, 
differing  from  the  preceding,  is  also  said  to 
have  been  recently  discovered  in  the  West 
Indies;  and  a  smaller  species  more  lately  in 
the  cove  of  Cork.f 

61.  But  among  the  singular  organic  re- 
mains derived  from  animals  which  occur  in 

*these  groups,  the  gigantic  and   monstrous 
lacertae  deserve  particular  notice.    Some  of 
these  inhabited  the  waters;   and  others  flit- 
ted through  the  air  like  birds,  or  rather  bats. 

62.  The  ichthyosaurus,  so  called  from  its  partly  resembling  a 
fish  and  partly  a  lizard,^  had  a  head  like  the  latter,  terminating 
anteriorly  in  a  long  pointed  muzzle,  armed  with  numerous  coni- 
cal  teeth.     It  had   a   long  tail,  capable  of  extensive  vibratory 
motion;  and  its  extremities  were  furnished  with   paddles  of  a 
peculiar  construction,  (see  subsequent  figure  of  the  plesiosaurus.) 

63.  The   succeeding  figure  represents  a  part  of  the  head  of 
the   Ichthyosaurus   latifrons.      The  socket    of  the  eye  measures 
about  9  inches  across,  whence  an  idea  may  be  formed  of  the  enor- 
mous  size  of  the  animal  to  which  this   head  belonged.     The 
Ichthyosaurus  communis  sometimes  exceeded   20  feet  in  length ; 
the  I.  platyodon  appears  to  have  had  jaws  8  feet  in  length  ;  and 
the  /.  immanis  was  a  gigantic  species  of  which  several  bones 
belonging  to  the  different  parts  of  the  skeleton  have  been  pre- 
served by  British  geologists. 

In  what  respects  do  the  pentacrinites  of  this  series  differ  from  the  en- 
crinites  of  the  lower  groups  of  rocks? 

By  what  local  name  has  this  fossil  been  distinguished  in  England  ? 
What  were  the  peculiarities  of  form  in  the  fish  lizard  ? 
What  was  the  size  of  its  eye? 


*  V.  Mem.  de  1'Acad.  des  Sciences  de  Pann.  1755. 

t  Bakewell's  Introd.  to  Geology — Prelim.  Obs.,  p.  35.  Mr.  Bakewell  has 
given  a  representation  of  the  latter  pentacrinus,  from  a  drawing  by  Mr.  J. 
V.  Thompson,  of  Cork. 

J  From  the  Greek  VCQvs,  a  /«*.  and  Eavposr  a  lizard. 
2N 


ORYCTOLOGY. 


64.  The  plesiosauri  constituted  another  genus  of  these  strange 
swimming  lizards.  Its  limbs  have  analogies  with  those  of  the 
foregoing  animal  :  but  more  elongated  and  flexible.  What,  how- 
ever, especially  distinguishes  it  from  all  oviparous  and  viviparous 
fjuadrupeds,  is  a  slender  neck,  as  long  as  its  body,  composed  of 
thirty  or  more  vertebrae.  An  idea  of  its  general  form  may  be 
obtained  from  the  following  figure,  representing  the  Plesiosaurus 
dolichoddrus. 


"  If  any  thing,"  observes  C  u  vier,  "  could  j  ustify  those  hydras  and 
other  monsters,  the  figures  of  which  are  so  often  presented  in  the 
monuments  of  the  middle  ages,  it  would  incontestably  be  this 
plesiosaurus."* 

65.  A  more  grotesque  and  monstrous  animal  than  either  of  the 

What  circumstance  distinguishes  the  plesiosaurus  from  all  the  known 
quadrupeds  ? 

*  Theory  of  the  Earth,  p.  257.  For  descriptions  and  figures  of  various 
species  of  ichthyosauri  and  plesiosauri,  see  Cuvier  Recherches  sur  les 
CJpsemens  Fossiles.  torn.  v.  pt,  ii. 


HYL.KOSAURUS.  423 

preceding,  is  exhibited  in  the  annexed  figure  of  the  fossil  skeleton 
™.^™,of   a    pterodactyle.    or    flyino-    lizard. 

,.-.,., "'"'"I  T«L.  f         -i 

I  Lhese  fossils   are   not  very  common: 
HHHHH  they  are  found  in  the  limestone  slates 
fflof  the  liasic  group,  at  Solenhofen,  in 
Hi|i  Germany  ;    at   Stonesfield,   in  Oxford- 
ire,  and  at  Lyme  Regis,  in  Dorset- 
H  shire.     One  species  was  about  the  size 
of  a  thrush,  another  of  that  of  a  com- 
mon bat;  and  the   remains  have   been   discovered    of  some   of 
larger  dimensions.* 

66.  The  wealden  group  is  not  less  remarkable  than   the  pre- 
ceding, for  its  fossil  remains.     Among  those  of  vegetable  origin 
may  be  mentioned  the  silicified  trunks  of  coniferous  trees,  and 
plants  allied  to  the  recent  genera  cycas,  and  za/ma,  which  have 
been  found  in  a  stratum  called  the  dirt-bed,  in  the  Isle  of  Portland. 
Many  of  the  stems  are  still  erect,  as  if  petrified  while  growing 
undisturbed  in  their  native  forest. f 

67.  But  the  animal  fossils  discovered  by  Mr.  Mantell  among 
the  strata  of  Tilgate  forest,  in  the  weald  of  Sussex,  are  more 
curious  and  interesting.   Besides  relics  of  crustaceous  and  testa- 
ceous animals  and  fishes,  he  has  been  enabled  to  recognise  those 
of  immense  saurian  reptiles,  some  of  which  were  before  unknown. 
To  one  of  these  animals  he  gave  the  appellation  of  iguanodon, 
from  its  affinity  to  the  iguana.    From  the  form  of  its  teeth  it  ap- 
pears to  have  been  herbivorous;  and  a  comparison  of  its  bones 
with  those  of  the  recent  iguana,  led  to  the  conclusion,  that  it 
must  have  been  fourteen  times  as  large,  or  not  less  than  70  feet  in 
length.  £ 

68.  In  the  summer  of  1832,  workmen  employed  in  quarrying 
the  Tilgate  grit,  found  a  hard  block,  in  which  were  embedded  a 
number  of  fossil  bones.    These  being  examined  by  Mr.  Mantell, 
were  ascertained    to   have   belonged    to   a  new  saurian  animal, 
which  he  described  in  a  paper  read  before  the  Geological  Society, 
and  afterwards  published.    He  gave  to  this  creature  the  name  of 
lltjkfosaurus,  or  wealden  lizard.     It  must  have  been  from  20  to  30 
feet  in  length,  and  appears  to  have  resembled  the  recent  Iguana 
cornuta,  in  being  armed  with  a  horn  on  the  forehead,  and  .a  row 

In  what  localities  has  the  pterodactyle  been  found  ? 

AVhat  was  the  size  of  this  animal  ? 

What  are  some  of  the  vegetable  fossils  of  the  wealden  group  of  rocks  ? 

To  what  geologist  do  we  owe  the  discovery  of  animal  fossils  in  that 
group? 

What  important  additions  have  been  made  to  the  list  of  saurian  animals 
by  Mantell  ? 

*  V.  Cuvier  Recherches,  u.  a. 

t  See  Mantell's  Geology  of  the  South-East  of  England,  chap,  xi, 

J  Idem,  pp.  304—316, 


424 


ORYCTOLOGY. 


of  spines  along  the  back  :  it  had  an  immensely  long  tail,  and  its 
body  was  covered  with  scales ;  whence  it  has  been  proposed  to 
call  it  Hylaeosaurus  armatus.* 

69.  In  the  formation  of  the  cretaceous  group  are  abundance  of 
organic  remains  of  vegetables  and  animals.  Besides  numerous 
shells,  and  relics  of  radiated  animals,  molluscs,  and  Crustacea, 
there  are  in  these  strata  some  curious  zoophytes.  Among  the  fos- 
sils that  may  be  regarded  as  characteristic  of  this  group,  may  be 
mentioned,  alcyonites,  echinites,  ammonites,  and  belemnites. 

70.  The  marginal  figure  repre- 
sents a  fig-formed  alcyonite,  of  a 
dark  red  colour,  where  the  surface 
is  not  concealed  by  its  cortical 
coat,  which  is  gray,  pervaded  by 
a  slight  tinge  of  red.  "The 
pedicle  and  the  opening  at  the 
superior  part  are  here  very  perfect. 
Slight  traces  of  lines,  passing  from 
the  pedicle  to  the  opening,  are 
discoverable  in  this  specimen,  and 
doubtless  point  out  the  arrange- 
ment of  fibres  by  which  the  animal  was  enabled  to  draw  in  and 
eject  the  water  which  supplied  it  with  food."f  "  The  recent  ani- 
mal, according  to  Count  Marsigli, 
is  of  the  form  of  a  fig,  being  at- 
tached to  the  rocks  by  branches 
proceeding  from  its  smaller  end;  its 
upper  part  being  a  little  flattened, 
with  a  hole  in  the  centre.  Its 
colour  resembles  that  of  tobacco  ; 
and  its  parenchymatous  substance, 
he  thinks,  cannot  be  compared  to 
any  thing  better  than  to  nut-galls, 
when  well  dried." 

71.  An  echinite  from  the  Kent- 
ish chalk  pits,  with  one  of  its 
spines,  is  exhibited  in  the  annexed 
figure.  Various  species  of  the  genera  echinus  and  cidaris  are 
found  fossilized  in  Wiltshire,  and  other  southern  counties  of  Eng- 
land, where  the  black  flint  most  abounds.  These  animals,  some- 
times called  sea-eggs,  are  common  in  a  recent  state. 

What  variety  of  organic  remains  has  been  discovered  in  the  cretaceous 
group? 

What  is  the  structure  of  the  fig  alcyonite  ? 

What  is  the  appearance  of  the  recent  specimen  of  this  zoophyte? 


*  See  Geology  of  the  South-East  of  England,  pp.  316—328, 
*•  Parkinson's  Organic  Remains,  vol.  ii.  pp.  96,  97. 


ANTHOPHYLLUM  ATLANTICUM. 


425 


The  accompanying  figure  is  a  representation  of  the  Plagiostoma 
dumosum,  found  by  Mr.  T.  A.  Conrad,  in  a  bluff  of  nummulite 
limestone,  at  St.  Stephens,  on  the  Tombeckbe,  Alabama.  It  was 
taken  from  near  low  water  mark,  where  the  bluff  was  100  feet 
high,  composed  throughout  of  different  classes  of  shells,  connected 
together  by  the  lime.* 

The  Anfhophyllum  atlanticum,  de- 
scribed by  Dr,  Morton,  in  the  Journal 
of  the  Academy  of  Natural  Sciences 
of  Philadelphia,  is  represented  in  the 
annexed  figure,  It  is  a  species  of  fos- 
sil polypus,  found  abundantly  in  the 
limestone  of  Gloucester  county,  New 
Jersey. 

72.  Two  genera  of  saurian  reptiles 
in  the  fossil  state  occur  in  the  creta- 
ceous rocks.  These  consist  of  a 

species  of  crocodile,  found  at  Meudon,  in  France;  and  the  Moso- 
saurus,  remains  of  which  were  first  discovered  in  the  quarries  of  St. 
Peter's  mountain,  near  Maestricht;  and  since  near  Lewes,  in  Sus- 
sex. This  creature  appears  to  have  been  nearly  24  feet  in  length.* 

Describe  the  fossil  polypus  found  in  the  American  cretaceous  group? 
Where  was  the  mososaurus  first  discovered  ? 


*  See  Morton's  Organic  Remains,  p.  60. 

t  See  Mantell's  Geology  of  the  South-East  of  England,  pp.  146—152 ; 
and  Cuvier  Recherches,  torn.  v.  pt.  4. 

2N-2 


126  ORYCTOLOGY. 


The  preceding  figure  exhibits  a  representation  of  a  fragment  ot 
the  lower  jaw  of  this  saurian  monster,  preserved  in  the  British 
Museum. 

73.  The  fossil  remains  of  the  unparalleled  saurian  animal, 
described  by  Dr.  Harlan,  under  the  name  of  basilosaurus,  were 
first  made  known  by  Judge  Bree,  who  transmitted  to  Philadelphia 
a  vertebra,  found  in  the  marly  banks  of  the  Washita  river,  in 
Arkansas  territory,  taken  from  a  skeleton  said  to  be  150  feet  long. 
In  the  course  of  the  year  1835,  there  have  been  obtained  from  a  lime- 
stone rock,  30  miles  north-west  of  Claiborne,  Alabama,  several  bones 
of  the  same  extinct  race.*    The  skeleton  was,  at  the  early  settle- 
ment of  that  state,  exposed  to  view  on  the  surface  of  the  rock,  for 
much  more  than  100  feet  in  length.     These  bones  have  been 
entirely  converted  into  limestone,  not  a  particle  of  animal  matter 
remaining ;  for  when  tested  with  muriatic  acid  the  whole  substance 
is  dissolved,  and  nothing  but  muriate  of  lime  is  obtained. 

Tertiary  Rocks. 

74.  In  the  formations  above  the  chalk,  the  organic  remains  in 
crease  in  number  and  variety ;  though  many  fossils  found  in  the 
lower  series  no  longer  occur.     Only  a  few  of  the  most  remarkable 
can  be  noticed  here.     Extensive  catalogues  of  shells,  distinguish- 
ing their  localities,  their  living  analogues  where  they  are  known, 
and  the  relative  ages  of  the  deposits  in  which  they  are  found,  have 
been  published  by  M.  Deshayes  and  Mr.  Lyell.f     The  Cerithium 
giganteunij  which  is  remarkable  for  its  size,  is  found  in  the  Lon- 
don and  Paris  basins. 

75.  The  most  extraordinary  shell  of  this  genus  f  Cm'Mmm)  is 
C.  giganteum.     It  is  turreted,  extremely  long,  and  transversely 
striated :  the  turns  in  their  upper  part  are   tubecular,  and   the 

Where  the  basilosaurus  ? 

What  is  supposed  to  have  been  the  length  of  the  latter  animal  ? 

What  circumstances  distinguish  the  Cerithium  giganteum  ? 

*  For  a  full  account  of  these  fossils  see  the  first  volume  of  the  Transac- 
tions of  the  Geological  Society  of  Pennsylvania,  p.  348.  For  the  accuracy 
of  the  description  and  of  the  drawing  of  Mr.  R.  C.  Taylor  accompanying 
them,  we  can  fully  avouch,  having  seen  the  bones  at  the  time  of  their  re- 
ception.— ED. 

t  Deshayes  Description  des  Coquilles  caracteristiques  des  Terrains 
Paris,  1831.  Lyell's  Principles  of  Geology,  vol.  Hi.  8vo.  1st  edit- 


PAL^OTHERIA.  427 

columella  has  one  fold.  These  enormous  shells  are  generally  a 
foot  in  length.  One  of  the  specimens  which  I  possess,  and  which 
has  lost  at  least  an  inch  or  two  of  its  length,  still  measures  14 
inches.  They  are  found  at  Grignon,  and  are  not  very  rare  :  they 
are,  however,  in  general,  very  much  injured  ;  very  seldom  indeed 
having  the  lip  and  sides  open  and  perfect.  Their  form  is  that  of 
a  winaing  turriculated  pyramid,  with,  in  general,  twenty  turns, 
heset  on  their  upper  part  with  a  row  of  nodular  tubercles,  and 
having  the  general  surface  lightly  and  transversely  striated.  The 
opening  is  oblong  and  oblique,  and  terminates  in  the  lower  part  in 
a  canal,  the  extremity  of  which  is  moderately  recurved  ;  and  the 
superior  part,  instead  of  forming  a  canal,  is  laterally  extended,  in 
the  manner  of  an  ear-like  process.  There  is  only  one  fold  on  the 
columella.  This  is,  undoubtedly,  the  largest  unilocular  univalve 
shell  that  is  known."* 

76.  During  the  long  period  of  the  deposition  of  the  tertiary  for- 
mations, quadrupeds  existed ;  several  of  which,  now  extinct,  dis- 
play peculiarities  of  form  and  structure.  To  the  researches  of 
Cuvier  we  are  indebted  for  the  discovery  of  the  genera  of  the 
palseotheria,  lophiodonta,  anoplotheria,  anthracotheria,  chseropotami, 
and  adapis. 

The  marginal  figure  represents  a 
lower  jaw  of  the  Palaeotherium 
maximum  of  Cuvier. 

77.  "The  palaeotheria  must 
have  resembled  the  tapirs,  among 
recent  animals,  in  their  general 
form,  and  in  that  of  the  head,  par- 
ticularly in  the  shortness  of  the  bones  of  the  nose,  which  announces 
that  they  must  have  had  a  small  proboscis  like  the  tapirs,  and 
lastly,  in  their  having  six  incisors  and  two  canine  teeth  in  each 
jaw;  but  they  resembled  the  rhinoceros  in  their  grinders,  (of 
which  those  of  the  upper  jaw  were  square,  with  prominent  ridges 
of  various  configuration,  and  those  of  the  lower  jaw  in  the  form  of 
double  crescents,)  as  well  as  in  their  feet ;  all  of  which  were 
divided  into  three  toes,  while  in  the  tapirs  the  fore  feet  have  four. 
It  is  one  of  the  most  extensively-diffused  genera,  and  most 
numerous  species  that  occur  in  the  deposits  of  this  period."f  The 
bones  of  these  extinct  quadrupeds  are  found  in  the  gypsum  quar- 
ries of  Paris,  and  in  other  parts  of  France. 

78.  Among  the  fossils  of  the  British  Museum  are  the  lower  jaws 

What  classes  of  quadrupeds  have  been  discovered  by  Cuvier  in  the  ter- 
tiary strata  ? 

To  what  class  of  recent  animals  has  the  palaeotherium  been  assimilated  ? 
In  what  respects  did  it  resemble  the  tapirs? 
In  what  localities  has  the  palseotherium  been  obtained  ? 

*  Parkinson's  Organic  Remains,  vol.  iii.  p.  71. 

t  Cuvier's  Theory  of  the  Earth,  p.  266.  See  also  Recherches,  torn.  iii. 
and  torn.  v.  pt.  ii 


428  ORYCTOLOGY. 

of  different  species  of  deinotheria,  part  of  an  upper  jaw,  and  de 
tached  teeth  ;  from  Eppelsheim,  in  Germany. 


The  above  figure  exhibits  a  lower  jaw  of  the  Deinotherlu^ 
g'gantetu»i  some  of  the  teeth  of  which  are  wanting  ;  but  in  which 
is  seen  one  of  the  very  singularly-formed  tusks,  or  weapons  with 
which  nature  had  armed  this  quadruped. 

Alluvial  Deposits  and  Bone  Caverns. 

79.  The  remains  of  several  animals  no  longer  in  existence, 
mingled  with  those  of  living  species,  occur  in  the  relatively  recent 
formations.  Among  these,  the  Mastodon  ohioticus  has  attracted 
particular  attention.  The  earliest  notice  that  occurs  of  this  animal 
is  in  a  letter  from  Dr.  Mather,  of  Boston,  to  Dr.  Woodward  ;* 
and  in  1740,  relics  of  the  mastodon  were  found  in  Kentucky,  on 
the  banks  of  the  Ohio.  Immense  quantities  of  its  bones  have 
since  been  discovered  in  America.  The  marginal  figure  is  a 

representation  of  a  lower 
jaw  of  the  M.  ohioticus. 
It  measures  about  three 
feet  along  the  base. 

80.  Cuvier  says,  the 
great  mastodon  was  as 
high  in  proportion  as  the 
elephant,  with  equally 
long  tusks,and  had  grind- 
ers covered  with  bristling 
points,  which  made  them 
long  be  considered  as 

What  constitutes  a  distinguishing  peculiarity  of  the  deinotherium  ? 
To  wkal  class  of  quadrupeds  did  the  Mastodon  ohioticus,  belong? 


See  Philos.  Trans.,  abridged  by  Jones,  vol.  v.  pt^  ii.  p.  159. 


MEGATHERIUM.  429 

those  of  a  carnivorous  animal.  Its  bones  were  extremely  large 
and  solid.  Its  hoofs  and  stomach  are  said  to  have  been  found  in 
such  a  state  of  preservation  as  to  be  recognisable ;  and  it  is  as- 
serted, that  the  stomach  was  filled  with  bruised  branches  of  trees. 
The  Indians  imagine  that  the  whole  race  was  destroyed  by  the 
gods  to  prevent  them  from  destroying  the  human  species.  This 
seems  to  be  a  proof  that  the  mastodon  was  extinct  before  America 
was  inhabited  by  man;  or  else  the  Indians  could  not  have  mis- 
taken this  phytovorous  quadruped  for  a  beast  of  prey.* 

81.  The  fossil  elephant,  called  by  the  Russians  the  mammoth, 
was  another  of  the  ancient  pachydermata,  thousands  of  the  car- 
cases of  which  were  dispersed  over  the  surface  of  the  earth,  from 
Spain  to  the  shores  of  Siberia,  and  throughout  North  America.  It 
was  one  of  this  species  that  was  found  in  the  beginning  of  the  pre- 
sent century,  at  the  mouth  of  the  river  Lena,  preserved  in  ice, 
and  of  which  the  skeleton  was  removed  to  St.  Petersburg.    This 
animal  differed  from  the  modern  elephants,  in  having  a  thick  coat 
of  long  hair  on  its  body  :  it  was  more  than  9  feet  high,  and  16  in 
length,  f 

82.  To  this  period  has  been  assigned  the  Megalonyx  jeffersonil^ 
a  quadruped  whose  bones  have  been  found  in  the  western  part  of 
Virginia,  in  a  cave  in  the  county  of  Green  Briar,  three  feet  be- 
neath the  surface  of  the  ground,  and  also  in  Big  Bone  cave  on  the 
line  dividing  White  and  Warren  counties,  Tennessee.^:  This  crea- 
ture, from  its  teeth  and  claws,  appears  to  have  resembled  the 
sloth  and  anteaters ;  but  in  size  it  must  have  equalled  the  largest 
oxen. 

83.  The  megatherium,  the  relics  of  which  have  been  discovered 
in  South  America,  exhibits  an  union  of  the  characteristics  of  the 
armadillos  and  the  sloths,  with  the  magnitude  of  the  rhinoceros. 
Its  claws  must  have  been  of  a  monstrous  length,  and  prodigiously 
strong ;  and  its  whole  frame  displays  excessive  solidity.     A  ske- 
leton of  this  animal,  found  at  Beunos  Ayres,  was  sent  to  Madrid 
in  1789  ;  and  one  more  recently  discovered  in  Paraguay,  was  con- 

What  superstition  have  the  Indians  in  regard  to  the  mastodon  ? 

What  light  does  their  belief  throw  upon  the  period  when  the  mammoth 
became  extinct? 

What  peculiarity  distinguished  the  fossil  elephant  from  the  existing 
species  ? 

Where  are  the  fossil  specimens  to  be  found  ? 
vln  what  localities  has  the  megalonyx  been  discovered  ? 

Where  did  the  megatherium  exist? 

*  V.  Recherches  sur  les  Oss.  Foss.,  torn.  i.  and  torn.  iii. 

t  See  Mr.  Brande's  Journal  of  Science,  vol.  viii.  p.  96  ;  and  Cuvier  Re- 
cherches, torn,  i.,  iii.  The  soft  parts  of  this  animal  had  been  so  completely 
protected  from  decomposition,  during  a  long  series  of  ages,  by  the  frozen 
matter  in  which  it  was  enveloped,  that  the  flesh  was  devoured  by  bears 
and  other  beasts  of  prey,  after  its  release  from  its  icy  sepulchre. 

\  See  Dr.  Troost's  Paper  in  the  Transactions  of  the  Geol.  Soc.  of  Penn- 
sylvania, vol.  i.  p.  236. — ED. 


430  ORYCTOLO^Y. 

veyed  to  England  by  Mr.  Woodbine  Parish,  and  presented  to  the 
Royal  College  of  Surgeons,  in  London.* 

84.  Contemporary  with  these  and  other  animals,  the  genera  of 
which  are  become  extinct,  were  hyenas,  bears,  tigers,  wolves, 
and  other  beasts  of  prey,  differing  only  in  species  from  those  now 
existing.  At  this  epoch,  remarks  Cuvier,  "  the  class  of  carnivora 
was  numerous  and  powerful."    The  palaeotheria,  and  other  mam- 
malia and  reptiles  of  the  tertiary  period,  having  been  destroyed  by 
some  convulsions  of  nature,  were  replaced  by  a  brute  population 
of  a  different  character,  and  these  in  their  turn  were  extirpated  by 
an  overwhelming  catastrophe,  which  must  have  preceded  the  ori- 
gin of  the  human  race. 

85.  The  bone  caverns,  with  their  contents,  and  the  osseous 
breccia  found  in  other  situations,  present  phenomena  connected 
chiefly  with  the  geological  formations  posterior  to  those  of  the 
tertiary  period.  Caves  containing  the  bones  of  bears  and  other  ani- 
mals have  been  long  since  noticed  in  Germany.  The  most  anciently 
celebrated  is  Baumanshole,  in  the  county  of  Blankenberg,  described 
by  many  authors,  especially  by  Leibnitz,  in  his  "  Protogaea."     It 
is  formed  of  several  caverns,  containing  abundance  of  stalactites 
and  the  bones  of  animals,  principally  bears.  The  caves  of  Gaylen- 
reuth,  in  Franconia,  and  Adelsberg,  in  Carniola,  have  also  attracted 
much  attention  ;  and  there  are  many  others,  but  it  does  not  appear 
that  among  the  bones  found  in  them  there  were  any  of  animals  be- 
longing to  the  lost  genera.f 

86.  In  England  several  bone  caverns  have  been  observed  ;  as 
that  of  Kirkdale,  in  Yorkshire,  discovered  in  1821,  and  examined 
a  few  months  afterwards  by  Professor  Buckland.     The  floor  of 
this  cave  was  formed  of  argillaceous  and  slightly  micaceous  loam, 
mixed  with  much  calcareous  matter,  and  coated  with  stalagmite  ; 
beneath  which  were  buried  bones  and  teeth  of  the  hyena,  tiger, 
bear,    wolf,    fox,    weasel,   elephant,   rhinoceros,    hippopotamus, 
horse,  hare,  rabbit,  water-rat,  and  mouse ;  raven,  pigeon,  lark,  a 
small  kind  of  duck,  and  a  bird  about  the  size  of  a  thrush.     From 
the  manner  in  which  these  relics  were  dispersed  over  the  bottom 
of  the  cavern  under  the  mud  deposit,  and  the  great  preponderance 
of  hyenas'  teeth  among  the  bony  fragments,  Dr.  Buckland  con- 
cluded that  this  place  had  been  a  den  of  hyenas,  at  a  remote  period, 

What  genera  of  existing  quadrupeds  were  found  at  the  period  when  the 
tertiary  rocks  were  deposited  ? 

How  near  is  man  placed,  in  the  succession  of  races,  to  those  of  the  ter- 
tiary period  ? 

To  w  hat  geological  period  do  the  bone  caverns  belong  ? 

In  what  country  were  they  first  observed? 

What  particular  animal  is  found  in  the  German  bone  caves  ? 

What  variety  of  bones  were  found  in  the  Kirkdale  cavern? 

*  For  an  account  of  the  megalonyx  and  megatherium,  see  Cuvier  Re- 
cherches,  torn.  v.  pt.  i. 

t  See  Prof.  Jamoson's  Geological  Illustrations  of  Cuvier's  Theory  of  the 
Earth.  Note  on  Caves  containing  Bones  of  Carnivorous  Animals. 


BRECCIAS.  431 

when  tigers,  elephants,  and  hippopotami,  were  among  the  brute 
population  of  that  part  of  the  surface  of  the  globe ;  that  the 
hyenas  had  brought  in  the  bones  of  other  animals  which  they 
made  their  prey  ;  and  that  this  state  of  things  was  suddenly  ter- 
minated by  an  irruption  of  a  diluvial  torrent,  which  buried  the 
drowned  and  previously  destroyed  animals  in  an  envelope  of 
mud.* 

87.  There  are  also  ossiferous  caverns  in  France,  which  have 
excited  particular  attention -on  account  of  the  occurrence  of  human 
bones  in  them,  together  with  those  of  other  animals.  In  the  ca- 
vern of  Bize,  in  the  department  of  Aude,  M.  Marcel  de  Serres  met 
with  a  small  number  of  human  bones,  mixed  with  those  of  extinct 
animals  and  with  land-shells,  in  a  calcareous,  stony  mass,  ce- 
mented by  stalagmite.  M.  Tournal  also  found  in  this  mass  and 
the  black  mud  above  it,  human  teeth,  and  the  fragments  of  rude 
pottery,  f 

88.  In  caverns  in  tertiary  limestone,  at  Poudres  and  Souvenargues, 
in  the  department  of  Herault,  and  in  a  cavern  near  Miallet,  in  the 
department  of  Gard,  human  bones  and  coarse  pottery  have  been 
discovered,  mingled  with  the  relics  of  lost  animals.:}:  These  phe- 
nomena gave  rise  to  a  controversy  as  to  the  probability  of  man 
having  been  contemporary  with  the  brutes  with  whose  remains 
his  own  are  now  intermixed.  After  noticing  the  arguments  on 
both  sides,  Mr.  Lyell  observes,  that  "  as  many  of  these  caverns 
may  have  served  in  succession  as  temples  and  habitations,  as 
places  of  sepulture,  concealment,  or  defence,  it  is  easy  to  conceive 
that  human  bones,  and  those  of  other  animals  in  osseous  breccias 
of  much  older  date,  may  have  been  swept  away  together  by  inun- 
dations, and  then  buried  in  one  promiscuous  heap.  It  is  not  on 
the  evidence  of  such  intermixtures  that  we  ought  readily  to  admit 
either  the  high  antiquity  of  the  human  race,  or  the  recent  date  of 
certain  lost  species  of  quadrupeds. "§ 

89.  Osseous  breccias  are  not  confined  to  caverns.  They  occur 
frequently  in  places  on  the  northern  shores  of  the  Mediterranean 
and  its  islands.  At  Cagliari,  Sardinia,  such  breccia  is  found  in  the 
clefts  and  small  caverns  of  a  tertiary  rock,  about  150  feet  above 
the  level  of  the  sea.  Dr.  Christie  describes  such  a  deposit  at  San 
Giro,  near  Palermo,  as  not  being  confined  to  the  cave  itself,  but  as 
forming  part  of  the  external  talus,  resting  upon  the  upper  tertiary 

What  circumstance  gives  particular  interest  to  the  bone  caves  of  France  ? 
What  question  has  been  raised  respecting  the  relative  times  at  which 
the  several  kinds  of  bones  were  deposited  ? 

What  inference  has  Lyell  formed  respecting  this  subject  ? 
In  what  situations  are  bone  breccias  found  ? 

*  See  Buckland  Reliquiae  Diluvianae. 

t  M.  de  Serres  Geognosie  des  Terrains  Tertiaires ;  ou  Tableau  dea 
Principaux  Animaux  invertebres  des  Terrains  marins  tertiaires  du  Midi 
de  la  France.  1829. 

t  Bulletin  de  la  Societe  Geologique  de  France,  torn.  ii. 

$  Principles  of  Geology,  vol.  iii.  p.  165. 


432  ORYCTOLOGY. 

beds,  with  a  thickness  of  about  20  feet,  The  bones  were  those 
of  the  elephant,  hippopotamus,  deer,  and  of  the  dog.  At  Gibraltar 
have  been  observed  breccias,  formed  by  the  bones  of  small  animals, 
which  seem  to  have  been  thrown  down  from  the  nests  of  hawks, 
which  build  in  fissures  of  the  rock.  They  are  cemented  together 
with  fragments  of  decomposing  limestone  by  ferruginous  matter. 
In  New  South  Wales,  osseous  breccias  have  been  found,  including 
the  bones  of  animals  now  known  to  exist  in  that  country. 

90.  When  the  bones  of  elephants  and  other  large  quadrupeds  were 
found  imbedded  in  the  earth  in  the  middle  ages,  it  was  conceived  by 
the  credulous  naturalists  of  that  time  that  these  were  human  relics. 
In  1577,  Felix  Plater,  professor  of  anatomy  at  Basle,  described  seve- 
ral fossil  bones  of  the  elephant,  found  at  Lucerne,  as  those  of  a 
giant  at  least  19  feet  high.     Some  immense  bones  having  been 
discovered  in  1613,  near  the  castle  of  Chaumont,  in  France,  a  sur- 
geon of  Beaurepaire,  named  Mazurier,  procured  them,  and  made 
a  public  and  no  doubt  a  profitable  exhibition  of  them,  as  the  re- 
mains of  a  gigantic  king  of  the  ancient  Gauls,  pretending  that 
they  had  been  inclosed  in  a  sepulchre  30  feet  in  length,  bearing 
the    inscription,  "  TEUTOBOCHUS  REX."      The  bones,  however, 
were  those  of  an  elephant. 

91.  At  a  subsequent  period,  Scheuchzer,  a  Swiss  philosopher, 
brought  forward  an  example  of  a  skeleton  of  more  moderate  dimen- 
sions, imbedded  in   hard   stone,   which   he  represented   as   the 
undoubted   relics   of  a  human  antediluvian.     He  published   an 
abridged  account  of  this  wonderful  fossil,  in  the  Philosophical 
Transactions,  1726  ;  and  he  made  it  the  subject  of  a  distinct  trea- 
tise, entitled  "Homo  testis  Diluvii."     Cuvier,  at  length,  ascer- 
tained that  this  alleged  anthropolite  (the  nature  of  which  had  been 
questioned  by  Camper  and  others)  was  a  petrified  lizard,  a  large 
extinct  species  of  salamander.* 

92.  There  is,  however,  at  the  British  Museum,  in  London,  a 
genuine  anthropolite,  from  Guadeloupe,  in  the  West  Indies.     It 
consists  of  a  considerable  portion  of  the  skeleton  of  a  woman  (the 
spine,  pelvis,  several  ribs,  one  arm,  the  leg  and  thigh  bones)  im- 
bedded in  a  block  of  calcareous  stone.     The  stone  is  a  kind  of 
travertin,  formed  of  land-shells,  slate,  and  fragments  of  shells  and 
corals  from  the  sea  ;  which,  like  rocks  of  a  similar  composition 
found  elsewhere,  has  acquired  a  great  degree  of  hardness.     It  is 
consequently  a  recent  petrifaction   in    an    alluvial    formation.  f 
Other  skeletons,  probably  those  of  Caraibs,  are  contained  in  the 
same  calcareous  rock  ;  and  one,  with  a  portion  of  the  head  re- 
maining, is  preserved  in  the  Museum  of  Natural  History  at  Paris. 

What  was  formerly  thought  of  the  bones  found  in  caverns  by  the  early 
naturalists  ? 

What  impositions  were  practised  upon  the  credulit 


What  did  Cuvier  find  to  be  the  true  character  of  Scheuchzer's  supposed 
anthropolite  ?    In  what  formation  have  true  human  skeletons  been  found  ? 

*  Bertrand  Lett,  sur  les  Rev.  du  Globe,  lett.  ix.  xvi. 
t  Jameson's  Illustr.  of  Cuvier,  pp.  406—410. 


ORGANIC  REMAINS.  433 

93.  In  the  course  of  geological  inquiries  in  the  United  States, 
abundant  evidence  has  already  been  furnished  that  the  organic 
remains  imbedded  in  the  rocky  strata  of  America,  are  on  a  scnle, 
both  in  point  of  abundance  and  magnitude,  corresponding  with 
the  grandeur  of  her  natural  scenery— her  mountains,  lakes,  rivers, 
forests,  and  prairies.     We  need  not  mention  more  than  the  Mega- 
lonyx  jt'Jftrsonii,  the  gigantic  mastodon,  the  megatherium  of  Cuvier, 
and  the  basdosaurus  of  Dr.  Harlan,  to  make  apparent  the  justness 
of  the  preceding  remark. 

94.  The  eastern  part  of  the  United  States  being  a  primordial 
region,  affords  comparatively  few  organic  remains ;  but  the  mid- 
dle, southern,  and  western  states,  both  east  and  west  of  the  Mis- 
sissippi, are  characterized  by  vast  numbers  of  shells,  bones,  casts 
of  mollusci,  trees,  and  plants,  including  multitudes  not  known  to 
exist  at  present  in  any  part  of  the  continent.     The  cretaceous 
group,  in  particular,  has  afforded  already  a  rich  harvest  to  the 
labours  of  American  oryctologists,  and  as  other  parts  of  the  geolo- 
gical series  become  better  known,  there  cannot  be  a  doubt  that  the 
more  ancient  inhabitants  of  the  planet  will  be  found  in  America, 
in  as  great  abundance  as  in  any  other  region  of  the  earth  hitherto 
explored. 

95.  The  group  just  mentioned  has  been  traced  through  New 
Jersey,  Delaware,   Maryland.  Virginia,   North  Carolina,   South 
Carolina,  Georgia,  Alabama,  Mississippi,  Tennessee,  Louisiana, 
Arkansas,  and  Missouri.*     "In  fact,"  says  Dr.  Morton,  "a  great 
part  of  the  level  country  between  the  Rocky  mountains  and  the 
Mississippi,  is  occupied  by  this  formation ;  and  I  have  also  seen 
some  fossils  from  thence  which  bear  a  strong  affinity  to  those  of  the 
lias  of  Europe." 

96.  The  evidence  of  identity  in  the  strata  thus  observed,  at  points 
scattered  over  a  space  more  than  three  thousand  miles  in  extent, 
rests  not  only  on  the  general  resemblance  of  the  mineral  sub- 
stances composing  the  strata,  but  more  especially  on  the  generic 
and  specific  accordances  in  the  fossil  shells,  which  are  found  in 
every  part  of  this  vast  extent  of  country.     "Thus,"  says  the 
author  just   cited,  "the   Ammonites  placenta,  Bacculites   ovatus, 
Gryphaeavomer,  Gryphaea  mutabilis,  Ostraea  falcata,  &c.,are  found, 
without  a  shadow  of  difference,  from  New  Jersey  to  Louisiana." 

97.  To  the  study  of  this  and  various  other  strata  containing  organic 
remains,  the  geologists  of  America  are  now  applying  themselves 
with  an  ardour  which  has  derived  fresh  impulses  from  every  new 
reward  of  their  labours.  The  hope  of  being  able  to  decide,  by  this 
kind  of  observation  and  comparison  of  animal  remains,  the  great 
question  in  regard  to  the  relative  time  of  deposition  of  the  several 

What  is  the  relative   importance  of  American  fossils  when  compared 
with  those  of  other  countries  ? 

In  what  part  of  the  United  States  do  the  primordial  strata  prevail  ? 
What  is  the  extent  of  the  cretaceous  group  of  North  America  ? 

See  Morton's  Organic  Remains,  pp.  14 — 25. 
2O 


434  ORYCTOLOGY. 

rocky  strata,  is  with  them  much  enhanced  by  a  circumstance  early 
noticed  by  William  Maclure,  Esq.,*  who  has,  with  justice,  been 
denominated  the  father  of  American  geology.  His  extensive 
travels,  on  both  the  European  and  the  American  sides  of  the  At- 
lantic, had  enabled  him  to  compare  "  the  vast  confusion  and  intri- 
cacy of  the  stratification  of  the  old  continent,  by  which  different 
classes  of  rocks  are  mixed  and  thrown  out  of  their  natural  posi- 
tions, with  the  fortunate  regularity  of  the  geology  of  our  continent, 
and  the  ease  with  which  the  science  may  be  studied,  from  the  well 
defined  boundaries  which  nature  has  given  to  the  different  classes 
of  rocks  running  in  the  same  direction  from  one  end  of  the  continent 
to  the  other ;  having  the  line  of  separation  so  distinct  between  the 
different  rocks  in  the  limits  of  each  class,  as  to  reduce  to  a  certainty 
the  place  that  each  occupies  in  the  natural  order." 

98.  "  This  results  from  the  fine  opportunities  afforded  of  examin- 
ing the  line  of  separation  at  every  junction,  through  a  distance  of 
twelve  or  fifteen  hundred  miles,  by  which  means  any  observer  can 
obtain  a  more  accurate  knowledge  of  geology  in  one  year,  in  the 
United  States,  than  he  could  in  a  long  life  spent  in  travelling  in 
any  other  part  of  the  globe  hitherto  examined  and  described.^" 

What  character  in  the  American  strata  renders  the  study  of  their  organic 
remains  easier  than  that  of  the  European  ? 

By  whom  was  this  advantage  first  pointed  out  ? 

*  President  of  the  American  Geological  Society,  and  of  the  Academy  of 
Natural  Sciences  of  Philadelphia, 
t  See  Silliman's  American  Journal  of  Science,  vol.  vii.  p.  257. 


WORKS  ON  ORYCTOLOOY.  435 


Works  in  the  Department  of  Oryctology. 

The  interest  of  the  subject,  and  the  importance  of  possessing 
resources  for  comparison  between  the  fossiliferous  beds  of  Europe 
and  those  of  America,  induce  us  to  add  here  a  rather  greater  num- 
ber than  usual  of  works  of  reference,  some  of  which  it  may  not 
be  easy  to  obtain  without  importing  them  expressly  from  Europe. 
We  have  ourselves  encountered  this  difficulty,  in  endeavouring  to 
procure  several  of  the  works  named  in  the  following  list: 

Morton's  Synopsis  of  Organic  Remains. 

Silliman's  American  Journal  of  Science,  vol.  xxix.,  and  many 
parts  of  the  preceding  volumes  of  the  same  work. 

Transactions  of  the  Geological  Society  of  Pennsylvania. 

Lea's  Contributions  to  Geology. 

Harlan's  Medical  and  Physical  Researches.  1  vol.  8vo.  Phila- 
delphia. 1835. 

Journal  of  the  Academy  of  Natural  Sciences  of  Philadelphia.  7 
vols.,  hitherto  published. 

Dr.  Jacob  Green's  Monograph  of  North  American  Trilobites, 
with  accompanying  casts. 

Parkinson's  Outlines  of  Oryctology.  1  vol.  8vo.  London.  1822. 

Sowerby's  Mineral  Conchology.  2  vols.  8vo.  1812. 

Alex.  Brogniart's  Tableau  des  Terrains  qui  compose  1'ecorce  du 
Globe. 

Transactions  of  the  Geological  Society  of  London.  5  vols.  4to. 

Deshayes,  G.  F.  Description  des  Coquilles  Fossiles  des  Envi- 
rons de  Paris. 

Cuvier,  G.  Recherches  surles  Ossemens  Fossiles. 

Essai  d'une  Expose  de  la  Flore  du  Monde  Primitive,  par  Gas- 
pard  Comte  de  Sternberg.  1  vol.  fol.  Leipsic  and  Prague.  1820. 

J.  S.  Miller's  Natural  History  of  the  Crinoidea.  1  vol.  4to. 
Bristol,  England.  1821. 

Vegeteaux  Fossiles,  par  M.  Adolphe  Brogniart,  Paris.  1822. 

Townsend  on  Fossils.  1  vol.  4to.  Bath,  England.  1813. 

MantelPs  Geology  of  the  South  Eastern  parts  of  England.  1 
vol.  4to. 

Witham's  Internal  Structure  of  Fossil  Vegetables.    1833. 


METEOROLOGY. 

1.  FEW  subjects  connected  with  natural  philosophy  are  more 
generally  interesting  than  that  which  is  about  to  engage  our  atten- 
tion. Meteorology  maybe  considered  as  a  science  supplementary 
to  geology  ;  and  as  the  latter  relates  to  the  state  and  constitution 
of  the  terrestrial  globe,  so  the  former  regards  the  composition  of 
the  atmosphere,  and  the  investigation  of  the  constant  changes  that 
are  taking  place  in  it.  "  The  quality  of  the  air,  as  affected  by  cold  or 
heat,  moisture  or  dryness,  and  other  circumstances,  is  distinguished 
by  the  term  weather.  The  knowledge  of  the  alterations  of  the 
weather,  and  of  the  laws  by  which  they  are  governed,  is  styled 
weather-wisdom,  (die  witterungslehre,')  or  meteorology. 

2.  "This  science  is  yet  very  imperfect,  and  requires  for  its 
improvement  numerous  and  extensive  observations."*    Notwith- 
standing, however,  the  confessedly  defective  state  of  this  branch  of 
physical  science,  it  is  certainly  one  which  has  occupied  the  atten- 
tion of  mankind  in  various  ages,  and  in  several  different  parts  of 
the  world  ;  but  it  is  only  in  our  own  times  that  it  has  been  studied 
with  the  attention  due  to  it,  both  in  an  economical  and  in  a  philo- 
sophical point  of  view.     To  the  navigator,  the  traveller,  the  hus- 
bandman, and  numerous  other  classes  of  persons,  the  state  of  the 
weather,  and  the  anticipation  of  the  probable  changes  that  may 
occur  in  it,  must  ever  be  topics  of  considerable  interest  and  im- 
portance ;  while  the  scientific  inquirer  will  feel  no  less  anxious  to 
trace  the  laws  by  which  meteorological  phenomena  are  regulated, 
and  to  study  their  connexion  with  those  of  astronomy  and  geology. 

3.  One  of  the  latest  and   most   distinguished   meteorological 
writers  remarks,  that  "  man  may  almost  with  propriety  be  said  to 
be  a  meteorologist  by  nature :  he  is  naturally  placed  in  such  a 
state  of  dependance  on  the  elements,  that  to  watch  their  vicis- 
situdes and  anticipate  their  disturbances  becomes  a  necessary 
portion  of  the  labour  to  which  he  is  born.     The  daily  tasks  of  the 
mariner,  the   shepherd,  and  the   husbandman,  are  regulated  by 
meteorological  observations  ;  and  the  obligation  of  constant  atten- 
tion to  the  changes  of  the  weather,  has  endued  the  most  illiterate 
of  the  species  with  a  certain  degree  of  prescience  of  some  of  its 
most  capricious  alterations.     Nor  in  the  more  artificial  forms  of 
society  does  the  subject  lose  any  of  its  universality  of  interest: 
much  of  the  tact  of  experience  is  blunted  and  lost;  but  artificial 
means,  derived  from  science,  supply,  perhaps  inadequately,  the 
deficiency  ;  and  the  general  influence  is  still  felt  and  acknowledged, 

What  is  meant  by  the  term  meteorology  ? 

What  is  the  actual  state  of  meteorology,  compared  with  other  branches 
of  physical  science  ? 

What  is  the  value  of  this  science  in  a  practical  point  of  view  ? 

*  Elements  of  Natural  Philosophy  by  Professor  Vieth,  (Germ.,)  p.  408. 

• 


EXTENT  OF  THE  ATMOSPHERE.  437 

though  not  so  accurately  appreciated.  The  generality  of  this  in- 
terest is,  indeed,  so  absolute,  that  the  common  form  of  salutation 
among  many  nations  is  a  meteorological  wish,  and  the  first  intro- 
duction between  strangers  a  meteorological  observation."* 

4.  Meteorology,  in  ^its  most  extensive  acceptation,  has  for  its 
object  not  merely  the  observation  of  atmospherical  phenomena,  or 
of  those  occasional  appearances  styled  meteors,  to  which  the  atten- 
tion of  common  observers  has  been  generally  limited,  but  it  like- 
wise includes  the  rationale  of  terrestrial  as  well  as  atmospherical 
phenomena,  whether  accidental  or  permanent,  which  depend  on 
the  action  of  heat,  electricity,  magnetism,  or  light.    Considered  in 
this  point  of  view,  the  subject  will  appear  to  be  of  immense  extent ; 
and  it  may  hence  be  characterized  as  the  application  of  the  laws  of 
pyronomics,  optics,  and  electro-magnetism,  to  the  study  of  nature. 

5.  To  take  any  thing  like  a  complete  survey  of  the  science  in 
all  its  bearings,  would  not  only  require  a  much  greater  space  than 
the  plan  of  this  work  will  allow,  but  would  also  render  it  necessary 
to  repeat  much  that  has  been  introduced  elsewhere,  in  illustration 
of  topics  discussed  in  some  of  the  preceding  treatises,  both  in  the 
former  and  in  the  present  volume.  This  essay  on  meteorology  will, 
therefore,  be  confined  to  the  investigation  of  the   influence  of 
moisture  and  temperature  on  the  state  of  the  atmosphere,  and  the 
explanation  of  the  nature  and  causes  of  the  most  important  meteoro- 
logical phenomena,  with  references  to  such  subjects  as  have  under- 
gone previous  discussion. 

6.  The  general  properties  of  the  atmosphere,  as  a  permanently 
elastic  fluid  encompassing   on  all    sides  the  solid  globe  of  the 
earth,  and  indefinitely  extended  from  its  surface,  have  been  pointed 
out  and  illustrated  in  the  treatise  on  Pneumatics.  It  has  been  stated, 
that  at  the  height  of  fifty  miles  the  air  does  not  possess  sufficient 
density  to  reflect  the  rays  of  light ;  and  though  it  is  not  improbable 
that  the  atmosphere  may  exist  at  a  still  greater  elevation,  yet  the 
speculations  of  Dr.  Wollaston  go  far  to  prove  that  it  must  have 
certain  limits,  beyond  which  the  ethereal  medium  must  be  of  such 
extreme  tenuity  as  to  occasion  no  appreciable  resistance  to  the  re- 
volutions of  the  planets  round  the  sun  :  for  if  they  revolved  in  a 
resisting  medium  like  the  air,  the  regularity  and  uniform  extent 
of  their  orbits  would  be  disturbed,  contrary  to  what  may  be  con- 
cluded from  a  comparison  of  astronomical  observations  made  at 
different  and  remote  periods.f 

What  evidence  does  the  intercourse  of  common  life  present  of  the 
general  interest  taken  in  the  subject  of  meteorology  ? 

What  range  of  inquiries  is  embraced  by  the  science  of  meteorology  ? 

In  what  relation  does  it  stand  to  the  imponderable  agents  explained  in 
other  departments  of  science? 

What  evidence  is  derived  from  astronomy  in  favour  of  the  finite  extent 
of  the  atmosphere? 

*  Daniell's  Meteorological  Essays  and  Observations,  2d  edit, 
t  It  should,  however,  be  remarked,  that  the  observations  of  astronomers 
during  a  period  of  even  two  thousand  years,  can  afford  no  conclusive  evi- 

2o2 


438  METEOROLOGY. 

7.  The  peculiar  temperaments  of  various  organized  beings 
qualify  them  respectively  for  the  several  situations  they  inhabit. 
The  deepest  abysses  of  the  sea  are  probably  destitute  of  animated 
beings,  but  the  gigantic  whale  can  descend  to  a  vast  depth  beneath 
the  surface  of  the  ocean,  though  breathing  the  air  like  man,  and 
consequently  unable  to  remain  deprived  of  it  but  for  a  com- 
paratively short  period  ;  and  the  polype  lays  the  foundation  of  his 
coral  cells  on  rocks  often  apparently  far  beneath  the  usual  abodes 
of  the  finny  tribes.  On  the  other  hand,  the  condor  dwells  in  the 
upper  regions  of  the  air,  and  wings  his  steady  flight  over  the  sum- 
mits of  Pinchincha  or  Chimborazo,  which  are  among  the  loftiest 
peaks  of  the  mighty  Andes.*  Inflamed  bodies  would  become  ex- 
tinguished for  want  of  air  at  the  height  of  about  20,000  yards 
above  the  sea ;  hydrogen  gas  would  no  longer  deserve  the  name 
of  inflammable  air  at  25,000  yards;  and  sulphur  would  be  incom- 
bustible at  30,000  yards,  if  it  was  possible  for  it  to  be  transported 
to  such  an  elevation. 

8.  The  temperature  of  the  atmosphere  diminishes  in  proportion 
to  the  elevation  above  the  level  of  the  sea.  The  degree  of  tem- 
perature, however,  is  further  influenced  by  other  causes,  and  should 
be  estimated  with  reference  to  the  normal  heat  of  plains,  whence 
may  be  deduced  the  direction  of  isothermal  lines  for  summer  and 
winter  ;f  depending  more  or  less  on  the  mass  and  configuration  of 
mountains;  the  strata  of  clouds  or  vapours  which  may  intercept 
the  radiation  of  heat  from  plains  below  ;  and  likewise  on  the 
winds  or  currents  of  air  passing  horizontally  from  one  zone  to 
another  of  a  different  temperature.^ 

What  examples  of  self-adaptation  is  exhibited  by  fish,  animals,  and  men  ? 
How  does  the  temperature  of  the  atmosphere  vary  ? 

dence  of  the  non-existence  of  a  highly  attenuated  but  resisting  medium, 
beyond  the  atmospheres  of  the  earth  and  other  planets.  For  though  it 
may  require  a  lapse  of  millions  of  ages  before  the  orbits  of  these  dense 
bodies  can  be  sensibly  affected  by  the  medium  they  traverse,  yet  lighter 
bodies,  such  as  comets  are  supposed  to  be,  may  afford  indications  that  the 
celestial  space  is  not  an  absolute  vacuum.  See  Treatise  on  Geology,  p.  316. 

*  We  have  been  informed  by  a  gentleman  who  has  spent  several  years 
in  the  Peruvian  mining  district,  about  12°  south  latitude,  and  at  an  eleva- 
tion of  16,000  feet  above  the  level  of  the  ocean,  that  he  has  repeatedly 
seen  the  condor  sailing  high  above  the  loftiest  of  the  snowy  Cordilleras 
with  no  apparent  motion  of  the  wings,  and  yet  in  an  air  so  attenuated 
that,  where  himself  was  stationed,  at  thousands  of  feet  below,  the  rarity  of 
the  atmosphere  rendered  all  effort  painful  to  those  not  long  accustomed  to 
the  light  medium  there  prevalent.  But  the  native  Indian  miners  exhibit 
nothing  of  the  same  inconvenience. — ED. 

t  These  have  been  also  denominated  isotheral  and  isocheimal  lines  ;  the 
former  signifying  lines  of  equal  temperature  for  the  summer  season,  and 
the  latter  lines  of  equal  winter  temperature.  See  Report  of  the  British 
Association,  1832,  pp.  217,  218. 

t  For  observations  on  the  extremes  of  heat  and  cold  which  have  oc- 
curred in  different  regions,  and  relative  to  the  mean  temperature  of  the 
poles  and  the  equator,  see  Scientific  Class  Book,  pt.  i.,  Pyronomics,  pp. 
282 — 285.  And  for  an  account  of  the  direction  and  extent  of  isothermal 


VARIATIONS  OF  ATMOSPHERIC  PRESSURE.  439 

9.  The  gravity  of  the  air,  and  the  continual  variations  taking 
place   in   it,  are  among  the   most   important   causes  of  several 
atmospheric  phenomena.     Abundance  of  facts  demonstrate  that 
the  weight  of  a  column  of  air,  of  any  given  diameter,  is  equal  to 
that  of  a  similar  column  of  water  33  feet  in  height,  or  of  a  column 
of  mercury  30  inches  high.  Such  is  nearly  the  amount  of  the  mean 
gravity  of  the  atmosphere  at  the  level  of  the  sea.*     Its  relative 
gravitating  force  or  pressure  must  of  course  decrease  in  ascending 
above  the  surface  of  the  earth  :  but  augmentations  and  diminutions 
of  that  force  are  observable  at  the  same  place,  which  must  there- 
fore arise  from  circumstances  independent  of  local  elevation. 

10.  These  alterations  of  atmospheric  pressure  may  probably 
have  a  considerable  effect  on  the  animal  creation.    They  are  indi- 
cated by  the  rising  or  depression  of  a  column  of  mercury,  in- 
closed in  a  glass  tube,  forming  the  well-known  instrument  called 
a  barometer.     It  has  been  computed,  that  the  weight  of  air  com- 
monly pressing  on  the  surface  of  the  body  of  a  man  of  middle 
size,  is  about  30,0001bs.,  hence  a -variation  of  height  in  the  mercu- 
rial column  of  only  a  single  line  must  indicate  an  alteration  of 
atmospheric  pressure  to  the  extent  of  about  84lbs. 

11.  The  variations  of  pressure  that  have  been  observed  are  either 
periodical  or  occasional.  The  horary  variations  are  the  most  import- 
ant.    From  the  observations  of  M.  Ramond,  it  appeared  that  the 
barometer  attained  its  maximum  height  at  9  A.  M.  and  at  11  p.  M.  ; 
and  its  minimum  at  4  A.  M.  and  4  p.  M.  These  variations  take  place 
with  greater  regularity  between  the  tropics  than  in  the  temperate 
zones  ;  and  we  learn  from  the  investigations  of  Humboldt,  that 
near  the  equator  the  barometer  attains  a  maximum  at  9  A.  M.  and 
p.  M.,  and  a  minimum  at  3  or  4  A.  M.  and  p.  M.  so  constantly, 
that,  in  almost  all  states  of  the  air,  the  height  of  the  barometer  will 
indicate  the  time  of  day.  The  causes  of  these  horary  oscillations 
are  somewhat   obscure  ;   though  it  appears   probable  that  they 
chiefly  depend  on  temperature. 

12.  The  occasional  variations  of  atmospheric  pressure  seem  to 
be  intimately  connected  with  the  direction  of  the  wind.  Theatre 
greatly  influenced  by  latitude.  "At  the  equator  they  may  be  said 

How  is  the  pressure  of  the  air  affected  by  the  height  to  which  we  ascend? 
How  are  variations  of  pressure  in  the  air  commonly  ascertained  ? 
To  how  many  sorts  of  variation  is  .the  pressure  of  the  air  subject  ? 
V^hich  of  these  deserve  most  attention  ? 

At  what  hours  of  the  day  do  the  maxima  and  minima  of  pressure  occur 
in  the  tropical  regions  ? 
To  what  purpose  might  the  horary  variation  be  there  applied  ? 

zones,  the  mean  temperatures  of  days,  months,  and  seasons,  and  the  extreme 
temperatures  of  climates,  see  Pomllet  Elem.  de  Physique  et  de  Meteoro- 
logie,  torn.  ii.  pp.  628 — 638  ;  and  Encyclop.  Metrop.,  vol.  iv.,  Meteorology. 
*  The  mean  height  of  the  barometer  at  London,  for  the  year  1788,  was 
29.96  inches  ;  for  1789,  29.79  in. ;  and  for  1790,  29.98  inches.  Dr.  Dalton's 
Meteorological  Observations  and  Essays.  2d  edit.,  1834  ;  from  Philosophi- 
cal Transactions. 


440  METEOROLOGY. 

to  be  almost  reduced  to  nothing ;  for  it  rarely  happens  that  any 
change  takes  place  to  interfere  with  the  regular  course  of  the  di- 
urnal tides.  A  hurricane  creates  almost  the  only  exception.  The 
amount  of  variability  increases  towards  the  poles,  in  a  great  mea- 
sure owing,  probably,  to  the  irregularity  of  the  winds  beyond  the 
tropics.  The  mean  amount  of  variation  may  be  stated  at  the 
equator  at  two  lines,  in  France  at  ten  lines,  in  Scotland  at  fifteen 
lines,  throughout  the  year;  but  this  quantity  has  its  monthly  os- 
cillations."* 

Winds. 

13.  The  atmosphere  may  be  considered  as  consisting  of  a  mul- 
titude of  concentric  strata,  the  density  of  which  decreases  in  pro- 
portion to  their  height  above  the  surface  of  the  sea.     While  an 
equilibrium  exists  between  the  different  parts  of  the  aerial  mass, 
it  remains  calm  and  tranquil ;  but  if  the  equilibrium  be  broken  by 
any  cause  whatever,  the  mass  becomes  agitated,  and  that  kind  of 
motion  in  the  air  takes  place  which  is  termed  wind.     Among  the 
general  causes  that  destroy  the  equilibrium  of  the  atmospheric 
strata,  the  most  common  are  change  of  temperature  or  pressure, 
tides,  and  great  currents  of  water,  the  rotatory  motion  of  the  earth, 
the  hygrometric  or  the  electric  state  of  the  air,  and  the  action  of 
the  sun  and  the  moon.  There  are  others,  the  influence  of  which  is 
less  extensive,  as  earthquakes  and  the  eruptions  of  volcanos. 

14.  Alteration  of  temperature  is,  perhaps,  the  most  usual  as  well 
as  the  most  important  cause  of  aerial  currents  or  winds.  When  one 
portion  of  a  mass  of  air  becomes  more  heated  than  those  parts  by 
which  it  is  surrounded,  it  is  rarefied  and  rendered  lighter  than  be- 
fore ;  so  that  it  ascends  to  a  higher  level,  while  the  adjacent  colder 
and  denser  air  rushing  in  to  supply  its  place,  streams  of  air  tend 
from  all  points  towards  that  where  the  partial  vacuum  has  thus  been 
formed.     Professor  Pouillet  remarks,  that  winds  may  be  propa- 
gated by  impulsion  and  by  aspiration.  We  designate  thus  the  two 
opposite  modes  which  ought  to  be  carefully  distinguished.  Wind 
is  propagated  by  impulsion,  when  it  blows  towards  a  place  in  one 
direction,  and  its  progressive  march  is  in  the  same  direction  :  thus 
it  is  with  the  wind  that  issues  from  a  pair  of  bellows,  when  the 
included  air  is  compressed. 

15.  Wind  is  propagated  by  aspiration,  when  the  blast  takes 
place  in  one  direction,  and  the  progressive  march  of  the  wind  is 

What  is  the  mean  amount  of  variation  in  pressure  in  high  and  in  low 
latitudes,  respectively  ? 

What  are  the  chief  causes  which  destroy  the  equilibrium  of  pressure 
in  the  air  ? 

In  what  manner  may  we  conceive  masses  of  air  to  be  set  in  motion  by 
heat  ? 

What  distinction  has  been'made  by  Pouillet  in  regard  to  the  directions 
in  which  wind  is  propagated  ? 

*  Forbes  on  Meteorology — Report  of  Brit.  Assoc.  for  1832.  p.  235. 


AERIAL  CURRENTS  441 

in  a  contrary  direction  :  this  is  what  happens  when  the  wind  en- 
ters a  pair  of  bellows  in  which  the  air  is  rarefied  ;  for  the  blast 
rushes  towards  the  nozzle,  but  the  progressive  march  of  the  cur- 
rent is  in  an  opposite  direction  ;  for  the  most  distant  points  whence 
the  air  is  drawn  last  receive  the  impression.  This  latter  mode  is 
not  so  unusual  as  might  be  imagined,  as  will  appear  from  the 
phenomena  of  hurricanes.  Wargentine  has  also  made  similar  re- 
marks on  the  winds  in  the  north  of  Europe.  He  says  :  "  When  the 
wind  proceeds  from  the  west  it  is  felt  at  Moscow  earlier  than  at 
Abo,  though  the  latter  city  is  about  400  leagues  farther  westward 
than  Moscow  ;  and  this  wind  does  not  reach  Sweden  till  after  it 
has  blown  over  Finland."* 

16.  The  manner  in  which  winds  are  produced  by  changes  of 
temperature  may  be  illustrated  by  some  simple  experiments.  The 
production  of  a  current  by  lowering  the  temperature  of  a  portion  of 
air  may  be  exhibited  by  means  of  the  ap- 
s  paratus  represented  in  the  margin.  Tie  a  piece 
of  wet  bladder  over  the  mouth,  C  D,  of  the 
bottle,  F  G  C  D,  after  having  poured  into  it  as 
much  water  as  will  half-fill  the  neck  when  the 
bottle  is  inverted.  Then  take  a  large  bladder, 
H  K  L  I,  and  cut  off  the  neck  of  it  in  such  a 
manner  as  to  leave  a  considerable  opening,  I 
H  ;  and  having  made  a  hole  in  it  at  K  L,  the 
neck  of  the  bottle  is  to  be  put  through  it,  and 
the  edges  of  the  bladder  must  be  tied  fast  round  the  bottle,  so  that 
no  liquid  may  pass  between  the  bladder  and  the  bottle.  Next 
throw  a  table-spoonful  or  two  of  common  salt,  and  as  much  again 
of  snow  into  the  bladder,  and  upon  the  globular  part  of  the  bottle, 
and  stir  them  together  with  a  stick  or  wooden  spoon.  The  snow 
and  salt  will  then  begin  to  melt,  absorbing  the  heat  from  the  bot- 
tle with  which  they  are  in  contact,  and  from  the  air  within  it, 
which  will  thus  become  cooled  down  to  such  a  degree  that  it 
would  freeze  the  water  in  the  neck  of  the  bottle  if  it  reached  above 
the  part  at  which  the  bladder  is  tied ;  and  as  this  mighUem- 
barrass  the  experiment,  but  a  small  quantity  of  water  should  be 

What  evidence  of  the  effect  of  aspiration  is  exhibited  in  the  north  of 
Europe  ? — What  in  America  ? 
Illustrate  this  effect  by  experiment  ? 

*  Pouillet  Elem.  de  Phys.  Exper.  et  de  Meteorol.  2nde  edit.  1832.  torn, 
ii.  pp.  715,  716. 

The  credit  of  having  established  the  fact  that  winds  blow  earlier  to- 
wards the  spot  at  which  the  greatest  disturbance  of  equilibrium  takes 
place,  at  points  near,  than  at  others  more  remote  from  that  spot,  is  due  to 
Dr.  Franklin — who  remarked  that,  along  the  Atlantic  coast  of  America, 
north-east  storms  begin  in  the  south-west,  and  proceed  to  windward  some- 
times at  the  rate  of  more  than  100  miles  per  hour.  The  observation  was 
strikingly  illustrated  in  the  case  of  a  solar  eclipse  being  visible  at  Boston, 
while  at  Charleston,  S  C.,  the  prevalence  of  a  north-east  storm  prevented 
its  being  seen. — ED. 


442  METEOROLOGY. 

introduced.  Now  the  air  within  the  bottle  being1  condensed,  and 
having  its  elasticity  weakened  by  the  deprivation  of  heat,  while  the 
external  air,  which  is  not  so  cold,  retains  more  expansive  power, 
it  will  force  its  way  into  the  bottle,  and  produce  a  current,  on  the 
bladder,  C  D,  being  punctured  with  a  large  pin  at  E.  The  air 
will  then  be  seen  rising  up  in  bubbles,  with  considerable  velocity, 
through  the  water  in  the  neck  of  the  bottle,  till  the  equilibrium  is 
restored  between  the  external  and  the  inclosed  air. 

17.  The  converse  of  the  preceding  experiment  may  be  performed 
by  slightly  varying  the  apparatus  already  described.   Take  a  bottle 
encompassed  with  a  bladder,  as  before,  and  leaving  it  open,  turn  it 
upside  down,  with  the  mouth  upon  a  plate  or  shallow  dish,  in  which 
has  been  put  a  sufficient  quantity  of  water  to  cut  off  the  connexion 
between  the  air  in  the  bottle  and  the  external  air.    Then  pour  hot 
water  upon  the  bottom  of  the  bottle,  and  into  the  bladder  surround- 
ing it.     The  heat  thus  applied  will  expand  the  air  in  the  bottle, 
which  will  issue  out  in  a  current,  through  the  water  in  the  plate, 
producing  a  mimic  wind,  that  may  be  felt  on  holding  the  hand 
near  the  place  where  the  air  escapes. 

18.  These  experiments  show  the  different  modes  of  propagation 
of  aerial  currents  which  Pouillet  has  indicated.  The  stream  of  air 
rising  through  the  water  into  the  first  bottle,  (in  which  a  partial 
vacuum  has  been  formed  by  reduction  of  temperature,)  is  obviously 
a  current  of  aspiration ;  and  that  issuing  from  the  second  bottle, 
through  the  expansion  of  the  included  air  by  heat,  is  a  current  of 
impulsion.  Each  of  these  methods  of  propagation  of  blasts  of  wind 
may  doubtless  be  sometimes  distinguished  ;  but  it  seems  probable 
that  winds  in  general  should  be  regarded  as  the  joint  effect  of  ex- 
pansion and  pressure  in  one  part  of  the  atmosphere,  and  condensa- 
tion in  another.     This  must  obviously  be  the  case,  since  but  for 
the  exterior  pressure,  air  would  have  no  tendency  to  rush  into  the 
void  created  by  condensation. 

19.  Some  interesting  "Facts  and  Observations  relating  to  the 
Winds,  Waves,  and  other  Phenoj»ena,  by  which  the  Surface  of 
the  Sea  is  affected,"  were  published  by  Captain  Horsburgh,  in 
Nicholson's  "Journal  of  Natural  Philosophy,"  which  serve  to 
show  that  a  descending  current  of  air   may  be  propagated  in 
various  directions.     He  says  :    "  I  have  several  times,  in  calm 
weather,  seen  a  cloud  generate  and  diffuse  a  breeze  on  the  surface 
of  the  sea,  which  spread  in  different  directions  from  the  place  of 
descent.      A  remarkable   instance  of  this  occurred   in   Malacca 
strait,  during  a  calm  day,  when  a  fleet  was  in  company  :  a  breeze 
commenced   suddenly  from  a  dense   cloud ;  its  centre  of  action 
seemed  to  be  in  the  middle  of  the  fleet,  which  was  much  scattered. 
The  breeze  spread  in  every  direction  from  a  centre,  and  produced 

How  may  the  production  of  wind  by  increase  of  temperature  be  illus- 
trated ? 

What  concurrence  of  causes  is  found  wherever  wind  is  produced  ? 

What  evidence  has  been  adduced  to  prove  that  the  descent  of 
of  air  may  produce  radiating  currents  of  wind  ? 


REGULAR  AND  VARIABLE  WINDS.  443 

a  singular  appearance  in  the  fleet,  for  every  ship  hauled  close  to 
the  wind  as  the  breeze  reached  her,  and,  when  it  became  general, 
exhibited  to  view  the  different  ships  sailing  completely  round  a 
circle,  although  all  hauled  close  to  the  wind."* 

20.  Captain  Horsburgh  afterwards  says  :  "  It  frequently  happens 
during  a  ty-fong  in  the  China  sea,  that  the  waves  run  in  every  di- 
rection ;  having  the  appearance  of  elevated  mounts  or  pyramids, 
which  infringe  on  each  other  with  great  violence.     Ships  are  very 
liable  to  lose  their  rudders,  when  these  pyramids  strike  against 
them ;  and  the  masts  are  endangered  by  the  quick,  turbulent  mo- 
tion proceeding  from  such  heterogeneous  impulse. "f     He  also 
states,  that  the  swell  of  the  sea  caused  by  a  storm  may  be  pro- 
pagated with  a  greater  mean  velocity  than  the  storm  that  causes 
it,  and  may  therefore  arrive  on  a  coast  before  it,  or  come  after  the 
storm  has  ceased.     These  phenomena  he  attributes  to  the  inter- 
ference of  contrary  winds. 

21.  Winds   may  be  distinguished  as  being  either  regular  or 
variable.     Among  the  former  are  the  trade  winds,  between  the 
tropics ;  the  monsoons,  in  the  Arabian,  Indian,  and  Chinese  seas  : 
and  the  sea  and  land  breezes. 

22.  Over  the  Atlantic  and  Pacific  oceans,  the  trade  winds  blow- 
ing permanently  westward,  extend  from  30°  N.  to  30°  S.  latitude. 
When  the  sun  is  on  the  equator,  the  trade  winds,  in  sailing  north- 
ward, veer  more  and  more  from  the  east  towards  the  north ;  so 
that  at  their  limit  they  become  nearly  NE. ;  and  on  the  contrary, 
in  sailing  southward,  they  become  at  last  almost  SE.     When  the 
sun  is  near  the  Tropic  of  Cancer,  the  trade  winds  north  of  the 
equator  become  more  nearly  east  than  at  other  times,  and  those 
south  of  the  equator  more  nearly  south ;  the  contrary  phenomena 
are  observed  when  the  sun  is  near  the  Tropic  of  Capricorn.     The 
trade  wind  becomes  due  east,  not  exactly  upon  the  equator,  but 
about  4°  N.  of  it. 

23.  These  intertropical  winds  are  the  effects  of  the  diurnal  ac- 
tion of  the  sun  in  raising  the  temperature  of  the  atmosphere  over 
those  points  of  the  earth's  surface  where  its  beams  are  vertical,  com- 
bined with  those  arising  from  the  earth's  motion  on  its  axis.   The 
lower  strata  of  the  atmosphere,  near  the  equator,  becoming  heated 
and  rarefied  by  the  sun,  form  ascending  currents,  spreading  towards 
the  poles ;  while  under  currents,  from  the  north  and  south  pole 
respectively,  flow  in  to  supply  the  partial  vacuum  caused  by  the 
condensation  of  the  air  over  the  equatorial  space.     The  polar  cur- 
rents, which  would  otherwise  meet  and  destroy  each  other  at  the 
equator  or  near  it,  are  modified  by  the  motion  of  the  earth  ;  f<§r  the 

What  peculiar  appearance  accompanies  the  ty-ftmg  of  the  China  sea  ? 
What  great  division  of  winds  is  founded  on  the  periods  of  their  pre- 
valence ? 

What  is  the  nature  and  what  are  the  directions  of  the  trade  winds? 

To  what  variations  are  they  liable  ? 

In  what  manner  have  the  trade  winds  been  explained  ? 

Nicholson's  Journal.  8vo.  vol.  xv.  p:  11-  t  Idem,  p.  12. 


444  METEOROLOGY. 

air  which  is  constantly  passing  from  points  where  the  surface  of 
the  earth  moves  most  slowly,  towards  those  where  its  velocity  is 
greatest,  cannot  have  exactly  the  same  motion  eastward  with  the 
part  over  which  it  is  passing,  and  therefore  must  relatively  to  the 
surface  beneath  it  form  a  current  in  an  opposite  direction. 

24.  Thus,  "  the  two  general  masses  of  air  proceeding  from  both 
hemispheres  towards  the  equator,  as  they  advance  are  constantly 
deflected  more  and   more    towards  the  east,  on  account  of  the 
earth's  rotation ;    that  from   the  northern  hemisphere,  orginally 
a  north  wind,  is  made  to  veer  more  and  more  towards  the  east,  and 
that  from  the  southern  hemisphere  in  like  manner  is  made  to  veer 
from  the  south  towards  the  east :  these  two  masses  meeting  about 
the  equator,  or  in  the  torrid  zone,  their  velocities  north  and  south 
destroy  each  other,  and  they  proceed  afterwards  with  their  com- 
mon velocity  from  east  to  west,  round  the  torrid  zone,  excepting 
the  irregularities  produced  by  the  continents."* 

25.  Beyond  the  range  of  the  trade  winds,  variable  winds  in 
general  prevail ;  though  between  the  two  there  is  a  zone  from  2 
to  6  degrees  in  breadth,  subject  to  the  occurrence  of  dead  calms, 
or  sudden  and  violent  tempests,  caused  apparently  by  the  con- 
fluence of  ascending  and  descending  currents,  between  which  there 
may  sometimes  be  an  equipoise,  and  at  others  rapid  alternations 
of  influence. 

26.  The  monsoons  are  periodical  winds,  blowing   about  six 
months  in  one  direction,  and  six  months  in  a  contrary  direction. 
From  10°  to  23°  S.  latitude,  in  the  Indian  ocean,  the  southern 
trade  wind  continues  regularly  from  the  east  and  south-east ;  but 
between  10°  S.  and  the  equator,  north-west  winds  prevail  from 
October  to  April,  and  south-west  the  rest  of  the  year  ;  while  north 
of  the  equator,  the  wind  is  south-west  in  summer,  and  north-east 
in  winter.     These  variations  appear  to  be  partly  owing  to  the 
position  of  the  sun,  and  partly  to  the  directions  of  the  great  chains 
of  mountains  in  the  countries  bordering  on  the  seas  over  which 
the  monsoons  prevail. 

27.  Sea  and  land  breezes  are  owing  to  the  same  grand  cause 
that  produces  the  trade  winds.     In  the  daytime,  when  the  reflec- 
tion of  the  sun's  rays  from  the  surface  of  the  earth  has  heated  the 
superincumbent  air,  it  rises ;  and  on  the  sea-coast,  currents  of 
cooler  and  denser  air  flow  in  from  above  the  sea,  to  replace  the 
ascending  mass.     At  night  the  converse  process  takes  place :  the 

How  do  the  north-easterly  and  the  south-easterly  trade  winds  affect  each 
oilier  «t  the  equator  ? 

What  states  of  the  atmosphere  prevail  immediately  north  and  south  of 
the  trade  winds  ? 

In  what  parts  of  the  earth  are  these  winds  liable  to  semi-annual  changes  \ 

To  what  are  the  monsoons  attributed  ? 

How  are  land  and  sea  breezes  explained  ? 

What  is  the  Etesian  wind  and  where  does  it  prevail  ? 

*  Dr.  Dalton's  Metereological  Observations  and  Essays,  essay  ii. 


VELOCITY  OF  WINDS.  445 

air  over  the  land  being  then  the  coolest,  the  night  breeze  sets  sea- 
ward, in  general  extending  two  or  three  leagues  from  the  shore. 

28.  A  diversity  of  local  winds  has  been  observed  in  different 
parts  of  the  world,  some  of  which  have  their  peculiar  designations. 
The  etesian  is  a  northernly  or  north-easterly  wind,  which  prevails 
very  much  in  summer  all  over  Europe.    Pliny  the  elder  describes 
it  as  occurring  regularly  in  Italy  for  forty  days  after  the  summer 
solstice.     It  is  probably  a  part  of  the  great  under  current  moving 
from  the  north  pole  to  the  equator.  The  sirocco,  felt  on  the  shores 
of  the  Mediterranean,  is  a  hot  blast  from  the  south,  prejudicial  to 
the  health  of  animals.     Such  also  is  the  harmattan,  a  warm,  dry, 
east  wind,  which  -is  perceived  on  the  Guinea  coast.     The  more 
deadly  kamsin,  which  occurs  in  Egypt,  and  the  simoom,  or  samyel 
of  the  Arabs,  a  destroying  wind,  which  is  said  to  have  proved 
fatal  to  whole  caravans  in  crossing  the  deserts,  are  supposed  to 
owe  their  properties  to  some  pestilental  vapours  mixed  with  the 
air. 

29.  Tempests,  hurricanes,  and  tornados,  are  atmospheric  com- 
motions of  the  more  violent  kind,  chiefly  taking  place  in  intertropical 
latitudes.  The  destructive  effects  and  extraordinary  force  of  these 
concussions  of  the  air,  may  be  conceived  from  the  statement  which 
has  been  previously  given  of  some  of  the  phenomena  of  a  hurri- 
cane in  Guadeloupe.* 

30.  Whirlwinds,  trombes,  or  syphons,  are  gyratory  or  vortical 
movements  of  the  air,  which  are  confined  to  no  country  or  climate  ; 
and  occur  at  sea  as  well  as  on  land.  In  fertile  regions  strong  trees 
and  buildings  are  sometimes  torn  up  by  the  impetuous  force  of 
whirlwinds ;  in  the  deserts  of  Africa  they  produce  moving  pillars 
of  sand,  such  as  are  picturesquely  described  by  the  celebrated 
traveller  Bruce;  and  at  sea  they  appear  in  the  form  of  water- 
spouts. 

31.  "The  relative  velocity  of  winds,"  says  Dr.  Dalton,  "  may 
be  best  ascertained  by  finding  the  relative  velocity  of  the  clouds, 
which  in  all  probability  is  nearly  the  same  as  that  of  the  winds. 
The  velocity  of  a  cloud  is  equal  to  that  of  its  shadow  upon  the 
ground,  which  in  high  winds  is  sometimes  a  mile  in  a  minute,  or 
sixty  miles  an  hour ;  and  a  brisk  gale  will  travel  at  the  rate  of 
twenty  or  thirty  miles  an  hour."|   The  velocity  of  hurricanes  has 
been  variously  estimated  at  from  100  to  300  feet  in  a  second.^: 

To  what  cause  is  the  poisonous  quality  of  certain  winds  supposed  to  be 
due? 

To  what  are  the  terms  tempest,  hurricane,  and  tornado  applied  ? 
In  what  different  characters  do  whirlwinds  present  themselves  ? 
How  may  the  relative  velocity  of  wind  be  ascertained  ? 

*  See  Treatise  on  Geology,  p.  334. 
t  Meteorological  Observations  and  Essays,  p.  90. 
t  See  Lamouroux  Geographic  Physique,  p.  103,  for  a  table  of  the  rela- 
tive velocities  of  winds. 


446  METEOROLOGY. 


Hygrometry. 

32.  Many  meteorological  phenomena  depend  on  the  presence  of 
water  as  a  constituent  part  of  the  atmosphere.    The  volatilization 
and  ascent  of  the  aqueous  fluid,  continually  taking-  place  from  the 
surface  of  the  earth,  produces  fogs,  mists,  and  clouds  ;  and  the 
corresponding  processes  of  condensation  and  precipitation  cause 
the  formation  of  rain,  snow,  dew,  and  hoar-frost. 

33.  Moisture  is  found  in  the  atmosphere,  either  in  the  state  of 
invisible  vapour,  or  in  the  form  of  minute  globules,  collected  in 
masses  of  varying  dimensions,  from  the  miniature  clouds  that 
ascend  from  a  basin  of  hot  water,  or  hover  above  the  surface  of  a 
small  pond  in  an  autumnal  morning,  to  those  vast  fields  of  mist  or 
haze  that  sometimes  cover  a  wide  tract  of  country.    These  collec- 
tions of  aqueous  spherules,  when  they  ascend  to  a  certain  height, 
constitute  the  different  configurations  of  clouds;  but  the  transition 
of  aerial  vapour  from  the  visible  to  the  invisible  state,  is  perpetually 
taking  place;  as  also  is  the  converse  change. of  invisible  vapour 
into  cloud. 

34.  The  quantity  of  moisture  in  the  atmosphere  is  thus  con- 
tinually varying,*  its  increase  or  decrease  depending  on  altera- 
tions of  heat  and  cold.     The  air,   however,  is   never  perfectly 
dry,  or   quite   deprived   of  water,  even  at  the   lowest   possible 
temperature,     f  According  to  the  experiments  of  Dalton,  Ure,  and 
Gay  Lussac,  as  well  as  the  calculations  of  Biot,  the  moisture  of 
the  air,  when  the  latter  is  perfectly  saturated,  has,  at  every  tem- 
perature, the  same  elastic  force  as  it  would  have  when  produced 
at  the  same  temperature  in  a  space  where  no  other  substance  was 
present.     Again  it  appears,  that  the  rate  of  expansion  of  vapour 
by  the  simple  application  of  heat  without  an  increase  of  water,  is 
the  same  both  when  alone  and  when  mixed  with  atmospheric  air, 
as  that  of  the  air  itself;  that  is,  taking  either  vapour  or  air  at 
32°  Fah.,  it  will  be  expanded  1 -480th  of  its  bulk  for  every  degree 
of  increase  in  temperature. 

35.  The  weight  in  grains  of  water  in  a  cubic  inch  or  any  other 
given  bulk  of  air,    may  therefore   be  found,  when  we  know  to 
what  temperature  the  air  and  moisture  must  be  brought  in  order 
that  perfect  saturation  should  exist.     The  following  short  table 
will  illustrate  the  case  just  stated. 

To  what  meteorological  phenomena  does  evaporation  give  rise  ? 

*  "The  atmosphere  is  not  of  uniform  composition;  the  quantity  of 
aqueous  vapour,  one  of  its  component  parts,  varies  almost  every  hour  of 
the  day.  It  is  subject  to  sudden  increase,  and  as  sudden  diminution  ;  and, 
in  its  ascent  to  higher  regions,  follows  a  very  different  Jaw  from  that  of 
the  permanent  elastic  fluids." — Daniell,  in  Brando's  Journal  of  Science, 
vol.  viii.  p.  324.  , 

+  See  Edinburg  Encyclopedia,  article  Hygrometry. 


HYOROMETRICAL  PHENOMENA. 


447 


Temperafcre 

Force  of  rapour  li 
an  inch  of  mercury. 

Weight  in  ?riinsof  the  water 
in  a  cubic  inch  of  vapour. 

Difference  in  weigm  of 
vapour  for  each  10  deg. 
increase  of  tempt-  ratun 
of    saturated    air    ex- 

Difference  between 
(he  re-pective  aug- 
mentations. 

millionth!  of  a  grain. 

0° 

.06120 

.00044957 

10 

.08931 

.00064161 

19204 

20 

.12927 

.00090882 

26721 

7517 

30 

.18561 

.00127758 

36876 

10155 

32 

.19934 

.00136636 

40 

.26436 

.00178229 

50471 

13595 

50 

.37345 

.00246714 

68485 

18014 

60 

.52320 

.00338832 

92118 

23633 

70 

.72688 

.00461639 

122807 

30689 

80 

1.00137 

.00623919 

162280 

39473 

90 

1.36785 

.00836386 

212467 

50187 

100 

1.85241 

.01111983 

274597 

62130 

From  the  fourth  and  fifth  columns  of  the  table,  it  appears,  that 
while  the  temperature  advances  in  arithmetical  progression,  the 
quantity  of  moisture  in  a  given  bulk  of  air  increases  with  the  ac- 
celerating rapidity  of  a  geometrical  series.  Hence  it  follows,  that 
if  two  portions  of  air  of  equal  bulks,  and  both  saturated  with 
moisture  at  different  temperatures,  be  mixed  together,  they  will 
inevitably  deposit  some  part  of  their  moisture. 

36.  [n  tracing  the  causes  of  meteorological  phenomena,  it  must 
obviously  be  a  point  of  importance  to  ascertain  the  hygrometric 
state  of  the  atmosphere  within  a  given  space,  or  the  quantity  of 
insensible  moisture  which  a  portion  of  air  contains.  The  barometer 
indicates  the  total  weight  of  an  aerial  column,  depending  partly  on 
the  invisible  vapour  which  enters  into  the  composition  of  the  lower 
strata ;  but  in  order  to  discover  the  relative  amount  of  that  vapour, 
various  circumstances  must  be  taken  into  consideration,  especially 
temperature  and  topical  elevation.     Hence  more  direct  means  are 
requisite  to  determine  the  proportion  of  moisture  in  the  atmosphere ; 
and  for  that  purpose  a  great  number  of  instruments  have  been  in- 
vented, styled  hygroscopes  or  hygrometers. 

37.  A  very  simple  apparatus  may  suffice  to  show  the  existence 
of  water  in  the  atmosphere.    Many  substances  are  naturally  so  far 
hygroscopic  that  their  weight  is  sensibly  influenced  by  the  state 
of  the  air.     Tobacco,  sponge,  salt,  sugar,  and  other  porous  sub- 
stances, imbibe   moisture   from  a  damp   atmosphere,   and   con- 
sequently become  relatively  heavier  than  when  the  air  is  in  a  dry 
state.  Sulphuric  acid,  potash,  and  muriate  of  lime,  each  powerfully 
attract  water  from  the  air  when  exposed  to  it,  in  almost  any  situa- 
tion.    Fibrous  bodies,  as  hair  and  thread,  become  contorted  and 
shortened  longitudinally  through  their  disposition  to  absorb  atmo- 
spheric moisture;     As   the  degrees  of  contraction  which   these 
bodies  undergo  admit  of  measurement,  they  have  been  very  gene- 
rally employed  in  the  construction  of  hygrometers. 

At  what  rate  has  the  vapour  in  the  air  been  found  to  increase,  compared 
with  the  temperature  1  What  is  the  kind  of  indication  afforded  by  a  ba- 
rometer? What  property  of  fibrous  bodies  renders  them  fit  to  indicate 
changes  of  the  atmosphere  in  regard  to  moisture  ? 


448  METEOROLOGY. 

38.  M.  de  Saussure  invented  an  instrument  of  this  kind,  which 
has  been  most  extensively  used  in  meteorological  researches.     It 
consists  of  a  hair,  (rendered  more  susceptible  of  the  influence  of 
moisture  by  steeping  it  in  a  weak  solution  of  potash,)  fixed  at  one 
extremity,  and  after  being  passed  round  a  pulley,  kept  extended 
by  a  small  weight  at  the  other  extremity.     On  the  axis  of  the 
pulley  an,  index,  moving  over  a  graduated  arc  of  a  circle,  indicates 
the  alternate  contraction  of  length  from  absorption  of  moisture,  and 
elongation  from  its  evaporation ;  and  thus  affords,  to  a  certain  ex- 
tent, a  measure  of  the  relative  quantity  of  aerial  vapour  at  different 
periods.     De  Saussure  adopted  some  ingenious  methods  to  deter- 
mine the  points  of  extreme  moisture  and  extreme  dryness  for  the 
scale  of  his  hygrometer.  He  obtained  the  latter  point  by  exposing 
the  instrument  under  a  bell-glass,  within  which  the  air  had  been  as 
far  as  possible  deprived  of  humidity,  by  means  of  concentrated 
sulphuric  acid,  or  calcined  muriate  of  lirne,  (chloride  of  calcium  ;) 
and  the  former,  by  placing  it  under  a  glass,  the  sides  of  which  were 
wetted  with  distilled  water,  and  standing  over  water. 

39.  In  spite,  however,  of  the  utmost  precaution  in  the  construc- 
tion of  these  hygrometers,  it  has  been  found  impossible  to  obtain 
two  instruments  that  exactly  correspond  in  their  indications ;  nor 
will  the  hygroscopic  power  of  an  individual  instrument  remain 
long  unaltered.  If  these  defects  could  be  avoided,  De  Saussure's 
hygrometer  would  only  afford  the  means  of  comparing  different 
degrees  of  humidity.     «*  We  might  ascertain   from  it  that  the 
humidity  of  the  air  was  at  60,  80,  or  100  degrees ;  but  we  should 
learn  nothing  concerning  the  elastic  force  of  the  vapour  contained 
in  that  air,  and  consequently   should  be  unable  to  resolve  the 
fundamental  question  which  involves  the  grand  object  of  hygro- 
metry.     For  that  purpose,  it  is  necessary  to  determine  what  is  the 
elastic  force  of  the  vapour  which  corresponds  with  each  of  the 
degrees  of  the  hair  hygrometer,  and  this  determination  is  very  dif- 
ficult ;  because,  for  example,  if  the  hygrometer  marks  80°  of 
humidity  when  the  temperature  is  at  zero,  and  80°  of  humidity 
also  when  the  temperature  is  at  30°,  the  corresponding  elastic 
forces  of  this  identical  indication  of  the  instrument  cannot  be 
equal.     Hence  further  researches  become  requisite  ;  and  M.  Gay 
Lussac  calculated  what  were  the  elastic  forces  of  the  vapour  cor- 
responding to  different  degrees  of  the  hair  hygrometer  for  a  given 
temperature,  fixing  on  that   of  10°.     He   found  that  when   the 
hygrometer  marks  100°,  the  elastic  force  is  at  its  maximum,  or  9.5 
millimetres;  at  60°  the  elastic  force  is  reduced  to  £;  and  at  30° 
to*. 

40.  Professor  Pouillet  remarks,  that  notwithstanding  the  im- 

What  is  the  construction  of  De  Saussure's  hygrometer  ? 

How  did  he  obtain  the  fixed  points  of  his  scale? 

To  what  serious  objections  is  this  instrument  liable  ? 

What  point,  in  regard  to  moisture,  is  it  important  for  us  to  ascertain? 

Why  may  not  De  Saussure's  instrument  determine  this  point? 

What  efforts  were  formerly  made  to  remedy  this  defect  I 


DEW-POINT  HYGROMETERS.  449 

portant  assistance  afforded  by  the  labours  of  M.  Gay  Lussac,  the 
hair  hygrometer  can  but  yield  approximative  estimates  of  the 
elastic  force  of  the  vapour  contained  in  air,  because  the  instrument 
is  irregular  in  its  indications,  and  liable  to  error.*  It  is,  however, 
probably  the  least  inaccurate  of  those  hygrometers  whose  action 
depends  on  the  change  of  dimensions  in  bodies,  owing  to  their 
absorption  of  vapour ;  and  as  it  has  been  very  extensively  em- 
p'oyed  by  men  of  science  in  making  meteorological  observations, 
some  notice  of  it  seemed  to  be  required. 

41.  Hygrometers  of  the  kind  just  described  can  at  best  supply 
only  a  part  of  the  information  requisite  towards  determining  the 
state  of  the  atmosphere  with  respect  to  its  aqueous  contents.  The 
quantity  of  invisible  vapour  in  any  mass  of  air  must  depend  on  the 
elastic  force  of  the  vapour,  or  its  disposition  to  retain  a  gaseous 
form,  and  that  again  will  be  chiefly  influenced  by  temperature.  The 
precise  object  of  hygrometry,  then,  should  be  to  determine  how 
much  moisture  the  atmosphere,  or  a  given  portion  of  it,  may  con- 
tain at  a  certain  temperature.     This  may  be  effected  by  ascertain- 
ing at  what  thermometrical  degree  a  body  of  air  begins  to  deposit 
its  moisture,  or  form  dew  ;  and  its  temperature  also  being  known, 
its  quantity  of  moisture  may  be  calculated. 

42.  The  degree  of  temperature  at  which  moisture  begins  to  be 
precipitated  is  termed  the  dew-point.^     The  manner  in  which  it 
varies,  relatively  to  the  state  of  the  atmosphere  as  to  heat  and 
moisture,  is  well  illustrated  by  one  of  Mr.  Daniell's  experiments. 
"  The  temperature  of  a  room  being  45°,  I  found  the  point  of  con- 
densation in  it  to  be  39°.     A  fire  was  lighted,  the  door  and  win- 
dows carefully  shut,  and  no  one  allowed  to  enter.  The  thermometer 
rose  to  55°,  but  the  point  of  condensation  remained  the  same.     A 
party  of  eight  persons  afterwards  occupied  the  room  for  several 

What  relation  exists  between  the  quantity  of  vapour  in  the  air  and  its 
elastic  force  ? 

On  what  does  the  latter  depend  ? 
What  is  meant  by  the  term  deu>point  in  meteorology  f 
How  may  the  variation  of  that  point  be  illustrated  l 


*  Poullet  Elem.  de  Phys.  et  Meteorol.,  torn.  ii.  pp.  737—741. 

t  Dr.  Dalton  was,  perhaps,  the  first  English  philosopher  who  pointed  out 
the  importance  of  the  dew-point,  as  a  hygroscopical  phenomenon,  in  a 
series  of  Essays  published  in  the  Manchester  Transactions,  vol.  v.  First 
Series.  But  a  kind  of  hygrometer  involving  this  principle  was  long  pre- 
viously invented  by  an  ingenious  Frenchman.  "  M.  le  Roy  prescrivoit, 
pour  moyen  hygrometrique,  de  tenir  dans  1'air  un  verre  plein  d'eau,  et 
dont  la  temperature  fut  la  meme  que  ceHe  de  1'air  ;  de  refroidir  lentement 
cette  eau  par  une  addition  graduee  et  successive  d'eau  a  la  glace,  et  de 
noter,  le  degre  de  froid  auquel  on  commeneeroit  a  voir  a  la  surface  du 
verre  cette  le"gere  rosee  qui  indiqne  la  precipitation  des  vapeurs,  et  par 
consequent  la  supersaturation  de  1'air  contigu  au  verre.  II  jugeoit  1'air 
d'autant  moins  humide,  qu'il  falloit  un  degre  de  froid  plus  considerable 
pour  operer  cette  precipitation." — Sigand  de  la  Fond  El6m.  de  Physique, 
fom.  iii.  p.  354.  V.  Le  Roy  Essais  sur-l'Hygrometrie,  p.  57. 

8P2 


450  METEOROLOGY. 

hours,  and  the  fire  was  kept  up.     The  temperature  increased  to 
58°,  and  the  point  of  condensation  rose  to  52°."* 

43.  Among  the  instruments  that  have  been  invented  to  ascertain 
the  hygrometric  state  of  the  atmosphere  with  relation  to  its  tem- 
perature, may  be  mentioned  the  hygrometers  of  Professor  Daniell 
and  of  Professor  Pouillet.     Both  consist  of  apparatus  adapted  to 
show  the  temperature  of  a  body  on  the  surface  of  which   dew 
begins  to  form,  and  which  may  be  compared  with  that  of  the  air 
from  which  it  is  precipitated. f 

44.  "  A  very  simple,  as  well  as  accurate,  method  of  taking  the 
dew-point,  is  to  use  a  thin  tumbler  of  tin,  kept  very  bright  and  clean 
on  the  outside — and  in  the  summer  cold  water,  and  in  the  winter 
snow  or  ice,  and  if  necessary  salt,  mingled  with  water — and  when 
these  are  not  at  hand,  a  mixture  of  muriate  of  ammonia  and  nitrate 
of  potash,  in   equal  quantities,  pounded  very  fine,  put  into  the 
tumbler  with  water.     By  any  of  these  means  a  temperature  may 
soon  be  obtained  below  the  dew  point.     When  dew  settles  on  the 
tumbler  it  must  be  carefully  wiped  off,  very  dry,  and  the  fluid  within 
Ktirred  with  a  thermometer — and  this  must  be  repeated  until  the 
fluid  is  gradually  heated  up  by  the  air,  so  that  the  moisture  ceases 
to  settle  :  the  highest  temperature  at  which  it  will  settle  is  the 
dew  point."     The  same  point  may  be  obtained  approximately  by 
the  following  method :  "  Take  two  thermometers  that  agree,  or 
allow  for  the  difference ;  cover  one  of  them  with  a  piece  of  wet 
white  cloth,  and  swing  them  simultaneously  in  the  air,  (unless 
the  wind  is  blowing  fresh;)  when  it  is  dicovered  that  they  cease 
to  change  by  swinging,  or  by  the  effect  of  the  wind,  take  103 
times  their  difference,  and  divide  it  by  the  wet-bulb  temperature, 
and  substract  the  quotient  from  the  temperature  of  the  naked-bulb 
— the  remainder  will  be  the  dew-point.     This  formula  is  founded 
on  experiments  from  20°  Fahr.  to  80°,  and  does  not  differ  at  either 
extreme  from  the  most  careful  experiments."^ 

Clouds. 

45.  Since  the  condensation  of  aerial  vapour  depends  on  the 
temperature  of  the  atmosphere,  it  is  manifest  that  it  may  exist 
in  a  much  larger  proportion  in  warm  climates  than  in  those  that 
are  colder.     Thus  the  air  in  the  cloudy  climate  of  England  is 

In  what  manner  may  the  dew-point  be  obtained  by  refrigeration  and  the 
use  of  a  common  thermometer  ? 

How  may  it  otherwise  be  approximately  obtained  ? 

*  Brande's  Journal  of  Science,  vol.  viii.  p.  321. 

t  For  a  descriptive  account  of  Daniell's  hygrometer,  see  papers  in 
Brande's  Journal  of  Science,  vol.  viii.  p.  300  ;  and  Met.  Essays  and  Obs. 
Pouillet's  Hygrometre  d  Capsule  is  described  in  his  Elem.  de  Phys.  et  de 
Meteorologie,  torn.  ii.  p.  733 ;  and  some  others,  constructed  on  similar 
principles,  are  noticed  by  Mr.  Forbes,  in  Report  of  British  Assoc.  for  1832. 

t  See  the  Circular  prepared  by  the  joint  commitees  of  the  Franklin  In 
stitute;  and  the  Philosophical  Society  of  Philadelphia. 


FORMATION  OF  CLOUDS.  451 

upon  the  whole  less  loaded  with  moisture  than  that  beneath  the 
clear  sky  of  southern  countries ;  and  consequently  more  rain 
generally  falls  during  a  year  at  Naples  than  in  London,  and  more 
at  Calcutta  than  at  Naples.  At  the  equator  the  air,  relatively  to 
its  temperature,  contains  less  moisture  than  in  the  temperate  zone, 
though  the  actual  amount  of  moisture  is  larger.  That  is,  the  air, 
near  the  surface  of  the  earth,  under  the  line,  has  a  greater  capacity 
for  moisture  than  air  at  the  same  height  in  colder  regions  ;  but  in 
thu  latter,  the  actual  quantity,  (though  smaller  in  a  given  bulk  of 
air,)  approaches  more  nearly  to  the  point  of  saturation,  without 
any  where  reaching  that  point ;  for  when  it  does,  precipitation 
takes  place. 

46.  "  Hence,  at  the  equator,  the  air  immediately  incumbent  on 
the  earth's  surface  must  be  comparatively  very  dry.     Moreover, 
the  cause  which  produces  the  dryness  of  the  equatorial  air,  at  the 
earth's  surface,  must,  all  over  the  globe,  exert  different  degrees 
of  the  same  influence.     The  air  every  where  incumbent  on  the 
earth's  surface  must,  therefore,  always  be  under  the  point  of  satu- 
ration; the  relative  degree  of  dryness  being  highest,  under  the 
equator,  and  gradually  diminishing  as  we  recede  north  or  south 
toward  the  poles.5'* 

47.  Clouds  consist  of  visible  vapour,  or  meteoric  moisture  in 
the   intermediate   state   between   invisible  vapour   and  palpable 
liquid.     Their  formation  appears  to  be  the  result  of  the  imperfect 
condensation  of  invisible  vapour,  from  the  intermixture  of  strata 
of  air  at   different  temperatures.     Evaporation    is    perpetually 
taking  place  from  the  surface  of  the  earth,  not  alone  from  seas, 
lakes,  &nd  rivers,  but  in  some  degree  from  the  hard  rock  or  the 
frozen  soil.f     The  watery  exhalations  are  usually  imperceptible, 
unless  when  a  rapid  change  of  temperature  occurs,  as  on  a  sudden 
thaw  after  a  hard  frost,  when  the  damp  earth  and  the  waters  throw 
off  abundance  of  reeking  vapour.     At  other  times,  the  transfer  of 
the  aqueous  fluid  from  the  earth  to  the  atmosphere,  though  not 
interrupted,  is  less  distinctly  observable. 

48.  "  During  the  heat  of  the  day  it  rises  from  the  surface  of  the 
land  and  waters,  and  reaches  its  point  of  condensation  in  greater  or 
less  quantities  at  different  altitudes.     Partial  clouds  are  formed 
in  different  parallel  planes,  which  always  maintain  their  relative 
distances.     The  denser  forms  of  the  lower  strata,  as  they  float 
along  with  the  wind,  show  that  the  greater  abundance  of  precipi- 

Considered  with  reference  to  the  temperature,  in  what  zones  is  the 
quantity  of  moisture  greatest  ? 

What  is  the  hygrometric  state  of  air  at  the  equator,  near  the  ground  ? 
What  is  the  nature  and  cause  of  clouds  ? 

*  Dr.  Prout's  Chemistry  and  Meteorology,  p.  287.  From  the  latter  part  of 
Dr.  Prout's  opinion  there  may  be  reason  to  dissent ;  for  though  the  abso- 
lute quantity  of  moisture  towards  the  poles  may  be  less,  the  difference 
in  high  and  low  situations  may  still  bo  as  great  as  in  the  equatorial  re- 
gions. The  air  at  the  surface  is  saturated  when  fogs  cover  it. — ED. 

t  See  Scientific  Class  Book,  pt.  i.  p.  308. 


452  METEOROLOGY. 

tation  has  been  at  the  first  point  of  deposition,  while  the  feathery 
shapes  and  lighter  texture  of  the  upper  attest  a  rarer  atmosphere. 
These  elouds  do  not  increase  beyond  a  certain  point,  and  often  re- 
main stationary  in  quantity  and  figure  for  many  hours  ;  but  as  the 
heat  declines,  they  gradually  melt  away,  till  at  length,  when  tfu3 
sun  has  sunk  below  the  horizon,  the  ether  is  unspotted  and  trans- 
parent. The  stars  shine  through  the  night  with  undimmed  lustre, 
and  the  sun  rises  in  the  morning  in  his  brightest  splendour.  The 
clouds  again  begin  to  form,  increase  to  a  certain  limit,  and  vanish 
with  the  evening  shades. 

49.  This  gradation  of  changes,  which  we  see  so  often  repeated 
in  our  finest  seasons,  may  at  first  seem  contrary  to  the  true  prin- 
ciples ;  and  the  precipitations  which  occur  with  the  increase  of 
temperature  and  disappear  with  its  c?:c/me,  may,  without  reflection, 
be  regarded  as  diametrically  opposite  to  correct  theory.  But  a 
little  consideration  will  show  that  such  conclusions  would  be  u,n- 
true.  The  vapour  rises,  and  is  condensed ;  but  in  its  descent 
falls  into  a  warmer  air,  where  it  is  again  evaporated,  and  becomes 
invisible ;  and  as  the  quantity  of  evaporation  from  the  surface 
of  the  earth  is  exactly  equal  to  supply  this  process  above,  the 
cloud  neither  augments  nor  decreases.  When  the  sun  declines, 
the  ground  cools  more  rapidly  than  the  air  ;  evaporation  decreases, 
but  the  dissolution  of  the  cloud  continues.  The  supply  at  length 
totally  ceases,  and  the  cloud  subsides  completely  away.  The 
morning  sun  revives  the  exhalations  of  the  earth,  the  process  of 
their  condensation  and  consequent  cloud-like  form  commences,  and 
they  again  undergo  the  same  series  of  changes."* 

.50.  Clouds  differ  from  fogs  only  in  their  superior  elevation  above 
the  surface  of  the  earth.  "They  are  seldom  a  mile  high  in  our 
climate  in  winter;  in  summer  they  may  perhaps  occasionally  be 
two  or  three  miles  high.  The  thickness  of  a  stratum  of  clouds, 
or  distance  from  the  under  to  the  upper  surface,  is  also  variable, 
from  a  few  yards  to  three  or  four  hundred  or  more.  A  stratum  of 
cloud  of  greater  depth  is  probably  of  rare  occurrence  any  where  ; 
it  would  produce  a  greater  degree  of  darkness  on  the  earth's  sur- 
face than  is  ever  observed. "f 

51.  Different  opinions  have  been  proposed  as  to  the  constitution 
«f  the  clouds.  They  are  usually  regarded  as  consisting  of  little 

JL 

In  what  part  of  a  series  of  clouds  does  the  precipitation  of  moisture  from 
the  invisible  state  appear  to  be  most  copious  ? 

What  succession  of  appearances  recurs,  during  fine  weather,  in  tempo  • 
rate  climates? 

How  is  this  reconciled  with  the  principles  of  greater  evaporation  being 
caused  by  higher  temperatures? 

What  is  probably  the  greatest  thickness  of  clouds  in  a  vertical  direction* 

*  Daniell's  Meteorological  Essays  and  Observations,  pp.  124,  12£. 

1  Dr.  Dal  ton's  Meteorolog,  Observations  and  Essays,  App,  to  2d  edition 
Note  -{A.]  The  sequel  of  this  note  contains  an  instructive  account  of 
phenomena  relating  to  clouds,  observed  during  excursions  in  the  more 
elevated  parts  of  several  counties  in  England. 


MODIFICATIONS  OF  CLOUDS.  453 

vesicles  of  water  filled  with  humid  air.*  As  to  the  cause  of  their 
ascent  or  suspension  in  the  atmosphere,  M.  Gay  Lussac  refers  it 
to  the  impulsion  of  ascending  currents,  owing  to  the  difference  of 
temperature  between  the  surface  of  the  earth  and  that  of  the  up- 
per air ;  while  M.  Fresnel  supposed  that  the  solar  heat,  absorbed 
by  clouds,  formed  groups  of  miniature  moritgolfieres,  which  rise 
to  heights  depending  on  their  excess  of  temperature  above  that 
of  the  air. 

52.  Dr,  Dalton  has  advanced  a  different  hypothesis,  considering 
clouds  as  being  composed  of  water  only,  in  a  state  of  extreme  di- 
vision.   He  says  :  "  When  a  precipitation  of  vapour  takes  place, 
a  multitude  of  exceedingly  small  drops  form  a  cloud,  mist,  or  fog  : 
these  drops,  though  eight  hundred  times  denser  than  the  air,  at 
first  descend  very  slowly,  owing  to  the  resistance  of  the  air,  which 
produces  a  greater  effect  as  the  drops  are  smaller."!  This  last  view 
of  the  nature  of  clouds  has  been  recently  brought  forward  by  Prof. 
Stevelly  at  the  Edinburg  meeting  of  the  British  Association.  He 
alleged  that  clouds  were  assemblages  of  spherules  of  water,  the 
production  of  which  might  be  accounted  for  by  the  laws  of  capil- 
lary attraction;  and  he  very  justly  remarked,  that  notwithstanding 
their  actual  specific  gravity,  compared  with  that  of  air,  "  the  mi- 
nute size  of  the  cloudy  spherules  would  alone  be  sufficient  practi- 
cally to  suspend  them,  as  even  gold  and  platina  may  be  so  subdi- 
vided as  to  descend  with  less  than  any  assignable  velocity.":*: 

53.  Either  of  these  theories  may  be  employed  to  account  for  the 
phenomena ;  but,  as  Professor  Pouillet  remarks,  "  We  at  present 
do  not  possess  sufficient  data  concerning  the  real  constitution  of 
clouds,  and  the  properties  of  the  vapours,  or  the  different  elements 
which  compose  them,  on  which  to  ground  a  satisfactory  explana- 
tion of  their  various  appearances."^ 

Modifications  of  Clouds. 

54.  The  ever-changing  varieties  of  form  which  clouds  exhibit 
to  the  eye  of  the  observer,  seem  to  bid  defiance  to  all  attempts  at 
classification.     The  task,  however,  has  been  undertaken  by  Mr. 
Luke  Howard,    who  after  a  long  series   of  meteorological   re- 
searches, formed   a   systematic  arrangement   of  clouds,   distin- 

What  opinions  have  been  advanced  to  explain  the  constitution  of  clouds  ? 
What  is  the  hypothesis  of  Gay  Lussac  ? 

How  has  Professor  Stevelly  sought  to  account  for  the  suspension  of 
the  spherules  of  visible  vapour  in  the  air? 

*  "  On  ad  met,  en  general,  que  les  vapeurs  qui  constituent  les  nuages  sont 
des  vapeurs  vdsiculaires,  c'est  a  dire,  des  amas  de  petits  globules  rernplis 
d'air  humide,  tout-a-fait  analogues  aux  bulles  de  savon." — Pouillet  EUm. 
de  Phys.  et  de  Meltorol.,  torn.  ii.  p.  753. 

t  Meteorological  Observations  and  Essays,  p.  134. 

i  Report  of  Professor  Stevelly's  Observations  in  the  Athenaeum,  for  Sept 
27,  1834. 

$  Elenou  de  Phys.  et  de  Meteorol.,  torn,  ii,  p.  754. 


454  METEOROLOGY. 

guishing  them  by  names  characteristic  of  their  general  structure 
and  mode  of  production.  The  classification  and  terminology  pro- 
posed by  this  ingenious  philosopher,  have  since  been  adopted  by 
many  writers ;  and  Mr.  Howard  himself,  after  eighteen  years'  ex- 
perience, thus  states  his  confidence  in  the  propriety  of  his  method  : 
"  I  do  not  find  a  necessity  either  to  make  additions  to  this  little 
system,  or  to  retrench  any  of  its  parts.  Some  subordinate  distinc- 
tions may,  indeed,  at  a  future  period,  be  found  useful  ;  but  until 
the  classification,  as  it  is,  be  generally  adopted,  its  simplicity  must 
•form  its  most  powerful  recommendation,  and  its  conformity  to 
nature.  It  is  in  the  form  and  structure,  carefully  considered  with 
due  reference  to  situation,  that  the  observer  will  find  the  basis  of 
a  correct  judgment ;  and  he  will  do  well  to  wait,  at  first,  for  se- 
veral successive  appearances  of  each  modification,  to  which  he 
will  thus  at  length  find  the  definition  apply  in  all  its  parts."* 

55.  The  modifications  of  clouds  are  distinguished  into  three 
principal  distinct  formations,  and  four  composite  kinds.    The  sim- 
ple forms  are  the  cirrus,  in  which  the  vapours  have  the  appear- 
ance of  loose,  narrow  bands  of  parallel  or  diverging  feathery 
fibres;  the  cumulus,  exhibiting  heaped  masses  of  a  globular  or 
conical  shape  ;  and  the  stratus,  forming  extended  level  sheets  of 
cloud.     The  composite  clouds  are  the  cirrocumulus,  consisting  of 
collections  of  small  but  well-defined  orbicular  masses,  or  little  cu- 
muli ;  the  cirro-stratus,  in  horizontal  or  somewhat  oblique  sheets, 
having  a  light,  fibrous  appearance  above,  and  a  concave  or  undu- 
lated surface  below ;  the  cumulo-stratus,  generally  flattened  at  the 
base,  and  heaped  above  with  overhanging  protuberances ;  and  the 
nimbus,  composed  of  dense  continuous  masses,  forming  a  canopy 
of  vapour  dissolving  below  into  rain. 

56.  Dr.  Thomas  Forster,  who  has  long  been  an   industrious 
observer  of  atmospheric  phenomena,  and  has  distinguished  him- 
self by  his  writings  on  meteorology,  has  adopted  Mr.  Howard's 
system,  which  he  has  endeavoured  to  familiarize  by  the  addition 
of  English  names  for  the  several  modifications  of  clouds.  To  the 
statement  of  these  terms  may  be  properly  added  a  few  notices  of 
the  modes  of  formation  of  the  different  varieties,  and  of  the  infer- 
ences that  may  be  drawn  from  their  appearance  relative  to  changes 
of  weather. 

57.  CIRRUS,  or  CURLCLOUD. — This  delicate  modification,  with 
its  varieties,  may  be  distinguished  by  its  fleecy  or  filmy  light- 
ness, fibrous  structure,  and  instabilty  of  form  ;  seldom  long  pre- 
serving the  same  appearance.     It  commonly  occupies  the  higher 
regions  of  the  air.     In  variable  and  warm  weather,  with  gentle 
breezes  in  summer,  long  obliquely  descending  bands  of  cirri  are 

What  nomenclature  lias  been  found  to  distinguish  the  several  kinds  of 
clouds  ? 

What  are  the  characters  of  the  several  compound  clouds  ? 

*  The  Climate  of  London,  deduced  from  Meteorological  Observations,  p.  L 


MODIFICATIONS  OP  CLOUDS.  455 

sometimes  seen  connecting  masses  of  other  modifications,  pre- 
viously to  rain.  After  a  continuance  of  fine  clear  weather, 
the  cirrus  may  be  seen  crossing  the  sky  at  a  great  height,  like 
a  white  thread,  the  extremities  of  which  seem  lost  in  the  horizon. 
This  is  called  the  Linear  cirrus.  When  several  of  these  long 
clouds  are  connected  by  transverse  or  oblique  processes,  they 
have  been  termed,  from  their  net-like  arrangement,  Reticular  cirri. 
the  most  usual  form  of  the  cirrus  is  that  called  the  Comoid, 
or  Mare 's-tail  cirrus,  which  commonly  occurs  in  variable  wea- 
ther, indicating  the  approach  of  wind  or  rain.  When  care- 
fully observed,  the  cirri  will  be  found  to  exhibit  signs  of  internal 
commotion,  without  any  change  of  place  ;  though  sometimes  the 
fibres  seem  to  wave  gently  to  and  fro.  This  happens  most  fre- 
quently in  those  large  and  lofty  cirri,  with  rounded  heads  and  long 
pointed  tails,  which  are  common  in  summer  and  autumn,  during 
the  prevalence  of  dry  winds. 

58.  CUMULUS,  or  STACKENCLOUD. — This   cloud  is  readily  dis- 
tinguished by  its  irregularly  hemispherical  figure,  having  gene- 
rally a  level  base.     It  is  produced  by  the  gathering  of  detached 
masses,  which  then  appear  stacked  or  piled  together.     Its  for- 
mation may  be  most  advantageously  traced  in  fine  settled  wea- 
ther.    About   sunrise,  small,  thinly-scattered  specks  of  clouds 
may  be  perceived  ;  which,  as  the  sun  ascends,  increase  in  bulk, 
coalesce,  and  at  length  form  the  complete  cumulus.     It  has  been 
termed  the  cloud  of  day,  as  it  generally  dissolves  in  the  evening, 
separating  first  into  small  fragments,  and  retracing  the  steps  of 
its  formation  in  a  reversed  order.     The  more  regularly-rounded 
cumuli,  of  a  whitish  colour,  which  reflect  a  bright  silvery  light 
when  opposite  the  sun,  are  the  harbingers  of  fine  weather ;  but 
those  of  a  more  indeterminate  figure,  with  a  dark  hue  and  irregu- 
lar fleecy  protuberances,  prognosticate  rain. 

59.  STRATUS,  or  FALLCLOUD. — The  stratus  is  nothing  more  than 
that  bed  of  vapour  which  covers  the  surface  of  the  earth  during 
the  absence  of  the  sun,  or  when  its  rays  are  impeded,  sometimes 
creeping  as  a  mist  over  the  valleys  and  low  lands,  and  disap- 
pearing soon  after  sunrise ;  and  at  others,  hovering  in  the  shape 
of  a  dingy  fog,  at  a  small  elevation  in  the  air,  during  one  or  per- 
haps several  days.     In  its  usual  form  of  a  summer-evening  mist, 
it  owes  its  origin  to  the  nocturnal  depression  of  temperature  in 
the  lower  region  of  the  atmosphere.     It  may  be  observed  in  a 
fine  evening,  after  a  hot  day,  when  the  cumuli  which  have  pre- 
vailed through  the  day  decrease,  that  a  white  haze  forms  close 
to  the  ground,  and  veils  its  surface.     About  midnight  it  attains 
its  utmost  density,  and  disappears  towards  sunrise.     It  has  hence 

In  what  states  of  weather  is  the  cirrus? 
Enumerate  some  of  its  varieties  ? 

What  is  found  to  be  the  action  of  the  parts  of  this  kind  of  clouds  among 
themselves  ? 

What  distinguishes  the  cumulus  from  other  forms  of  clouds? 
By  what  familiar  name  is  it  designated  ?    Why  ? 


456  METEOROLOGY. 

been  called  the  cloud  ofni^ttt.  In  autumn  the  longer  continuance 
of  this  cloud  marks  the  diminution  of  the  sun's  power.  But  in 
winter  it  sometimes  assumes  the  form  of  a  dense  fog,  shrouding 
in  dismal  darkness  every  object  on  the  earth,  especially  in  the  atmo- 
sphere of  some  large  cities  ;  the  obscurity  being  augmented  by  the 
intermixture  of  smoke  with  the  watery  vapour.  In  January,  1814, 
one  of  these  fogs  pervaded  the  air,  over  a  great  part  of  the  south 
end  west  of  England,  for  about  a  fortnight.  The  stratus  is  often 
found  to  be  positively  electrified ;  and  hence  it  does  not  wet  ob- 
jects in  contact  with  it.  This  modification  must  not  be  con- 
founded with  some  varieties  of  cirrostratus,  which  resemble  it  in 
appearance ;  but  the  latter  wets  every  thing  it  touches,  and  thus 
the  two  forms  may  be  distinguished. 

60.  CIRROCUMULUS,  or  SONDERCLOUD*— The  name  of  this  cloud 
indicates    its  affinity  to  two   of  the   principal  forms.     It   differs 
from  some  varieties  of  the  cirrostratus,  by  the  superior  density 
and   compactness   of  its  component   nubeculae,  and   the  greater 
diversity  of  arrangement.     At  the  approach  of  thunder  storms  cir- 
rostrati  appear   in  masses  of  a  denser  structure,  more  rounded 
shape,  and  in  closer  order  than  at  other  times.     In  rainy,  change- 
able weather,  these  clouds,  have  a  light,  fleecy  texture,  and  varia- 
ble figure,  being  scarcely  to  be  discriminated    from   cirrostrati. 
In  summer  the  cirrocumulus  forebodes  heat;  and  in  winter,  the 
breaking  up  of  frost,  and  approach  of  mild,  wet  weather. 

61.  CIRROSTRATUS,  or  WANECLOUD. — From   its   disposition    to 
rapid    alteration    of  figure   and    subsidence,  this   kind   of  cloud 
has   derived    its  English   appellation.    It   is  remarkable  for  its 
shallow   depth   relatively   to   its   horizontal    extent;    while    in 
other  respects  it  is  constantly  varying.    It  originates  more  fre- 
quently from  the  cirrus  than  from  any  other  modification  ;    and 
sometimes  after  descending  from  a  higher  station,  and  assuming 
its   characteristic  figure,  it  changes  again  into  cirri ;    but  more 
commonly  it  either  evaporates,  or  unites  with  some  other  kind 
of  cloud,  producing  cumulostratus,  nimbus,  and  then  falling  in 
rain.     Besides  its  common  appearance,  as  a  long,  plain  streak  of 
cloud,   tapering   towards   the   extremities,  it    assumes  the  form 
of    the    Mottled  cirrostratus,    constituting   what    is    called   the 
mackerel-back  sky  of  summer  evenings,  which   has  been   pro- 
verbially reckoned  a  sign  of  dry  weather.     The  Cymoid  cirrus 
is  accounted  a  variety  of  the  cirrostratus.     It  is   composed   of 
waving   bars   or   streaks,  either  arranged   so   as   to  form  lines, 
or   otherwise  disposed.     It  is   sajwl   to  be  a  sure  indication   of 
approaching  storms.    Another  variety  of  the  cirrostratus  is  that 
large  shallow   veil   of  cloud   which   occurs   especially  towards 

At  \vhat  hour  of  the  day  is  the  stratus  most  dense  ? 
To  what  designation  has  this  circumstance  given  rise  ? 
What  inihi  :I:IMMS,  in  regard  to  weather,  are  supposed  to  be  afforded  by 
the  cirrocumulus  ? 

What  is  the  familiar  appellation  applied  to  the  mottled  cirrostratus? 
What  is  supposed  to  be  prognosticated  by  the  cymoid  cirrus! 


RAIN,  HAIL,  AND  SNOW.  457 

night,  and  through  which  the  sun  and  moon  appear  but  indis- 
tinctly. Halos,  parhelia,  &c.,  usually  are  formed  by  peculiar 
refractions  of  the  light  of  those  bodies  in  this  variety  of  cloud. 
It  betokens  rain  or  snow. 

62.  CUMULOSTRATUS,  or  TWAINCLOUD. — This  modification   of 
cloud  is  produced  by  the   accumulation  of  other  kinds,  as   the 
cirrus  and  cumulus.   The  cumulus,  driven  by  the  wind,  becoming 
retarded  in  its  course,  grows  denser,  spreads  laterally,  and  swells 
out  into  a  dark,  irregular  mass.     Sometimes  a  number  of  cumuli 
unite  at  the  base,  from  which  heaps  of  vapour  rise  in  the  form  of 
mountain  peaks,  or  detached  rocks.     The  cumulostrati,  which 
give  birth  to  storms  of  hail  or  thunder  and  lightning,  often  look 
black  and  lowering,  especially  before  the  shower  of  hail  or  rain 
begins  to  fall.     Occasionally,  the  clouds  of  this  modification  eva- 
porate, or  the  mass  separates  into  cumuli ;  but  more  commonly 
their  appearance  is  followed  by  that  of  the  nimbus,  producing  rain 
or  snow. 

63.  NIMBUS,  or  RAINCLOUD. — Any  of  the  other  modifications 
of  clouds  may  form  and  again  disperse,  or  become  evanescent; 
but  the  nimbus  is  a  constant  precursor  of  a  storm.     It  may  be 
best  observed  when  showers  fall  at  a  distance,  and  the  nimbus 
can  be  seen  in  profile.     The  progress  of  its  formation  may  be  infer- 
red from  what  has  been  just  described,  under  the  preceding  modi- 
fication.    The  cumulostratus  having  been  formed,  sometimes  goes 
on  increasing  in  density  till  the  whole  horizon  is  veiled  in  por- 
tentous darkness.    Shortly  after  which  the  lowering  sky  assumes 
a  gray  obscurity,  denoting  a  new  arrangement  of  the  particles  of 
vapour  in  the  cloudy  mass.    The  nimbus  is  then  formed,  and  rain 
descends.     The  shower  continues  till  the  nimbus  is  exhausted, 
and  other  modifications  of  cloud  reappear :  the  cirrus,  the  cirros- 
tratus,  or  perhaps  the  cirrocumulus,  are  seen  aloft,  floating  amidst 
the  blue  sky ;  and  the  remaining  cumulus,  no  longer  retarded, 
sails  along  with  the  wind  nearer  the  surface  of  the  earth. 

Rain,  Snow,  and  Hail. 

64.  One  immediate  cause  of  rain  is  probably  the  intermixture  of 
masses  of  air,  whose  common  temperature  is  insufficient  to  keep 
suspended  their  joint  amount  of  moisture,  part  of  which  is  therefore 
precipitated.     Another  is  the  ascent,  into  an  elevated  region,  of 
warm  air  fully  supplied  with  vapour,  whereby  an  expansion*  and 
an  increase  of  capacity  for  heat,  with  a  diminution  of  temperature, 

What  forms  does  the  cumulostratus  exhibit  previous  to  a  hail  storm  or 
thunder  shower  ?     How  does  the  nimbus  differ  from  other  forms  of  clouds  ? 
What  are  supposed  to  be  the  two  immediate  causes  of  rain  ? 

*  The  effect  of  sudden  expansion  in  the  receiver  of  an  air-pump  is  to 
cause  invisible  to  change  for  a  moment  to  visible  vapour,  and  to  fall  in 
miniature  rain.  Before  reaching  the  pump-plate  this  little  shower  will 
sometimes  be  seen  to  disappear  as  the  temperature  resumes  its  former 
state.— ED. 

2Q 


458  METEOROLOGY. 

takes  place.  Contending  currents  in  the  atmosphere  bring,  sud- 
denly, into  mutual  contact  vast  fields  of  moist  air,  and  the  aqueous 
particles  coalescing  form  drops,  which,  if  the  temperature  is  above 
the  freezing  point,  descend  in  liquid  showers.  The  size  of  the 
drops  of  rain  probably  depends  on  the  degree  of  rapidity  with 
which  condensation  takes  place;  and  the  rate  at  which  they  de- 
scend must  be  influenced  by  the  relative  height  of  the  clouds,  the 
action  of  the  wind,  and  their  own  magnitude. 

65.  The  mean  quantity  of  rain  that  falls  in  different  parts  of 
the  world  varies  considerably,  according  to  local  circumstances. 
Among  these  are  temperature,  distance  from  the  sea,  and  position 
with  respect  to  mountain  chains.  According  to  Humboldt,  nearly 
six  times  as  much  rain  falls  at  the  equator  as  in  60°  N.  latitude. 
But  in  the  tropical  regions  the  rains,  though  vastly  more  abundant 
than  in  cold  climates,  are  much  less  frequent ;  and  in  the  former, 
the  rains   are  periodical.     Mountainous  tracts  are  visited  with 
more  copious  and  frequent  showers,  in  general,  than  plains ;  and 
in  some  countries  little  or  no  rain  falls,  as  in  Egypt,  the  fertility 
of  which  depends  on  the  periodical  inundations  of  the  Nile. 

66.  It  has  been  repeatedly  remarked,  that  in  any  given  situation 
the  quantity  of  rain  is  greatest  at  the  least  elevation  :  thus  more 
might  be  collected  within  an  area  12  inches  square  at  the  bottom 
than  at  the  top  of  a  high  tower,  all  other  circumstances,  except 
the  height  above  the  ground,  being  equal.     An  experimental  in- 
vestigation of  the  cause  of  this  phenomenon  has  been  undertaken 
by  Mr*  John  Phillips,  of  York,  England,  an  account  of  which 
may  be  found  in  the  Report  of  the  British  Association  for  1833. 
The  hypothesis  which  he  proposes,  as  a  probable  inference  from 
the  result  of  his  researches,  is,  "  that  the  whole  difference  in  the 
quantity  of  rain  at  different  heights  above  the  neighbouring  ground, 
is  caused  by  the  continual  augmentation  of  each  drop  of  rain  from 
the  commencement  to  the  end  of  the  descent,  as  it  traverses  suc- 
cessively the  humid  strata  of  air  of  a  temperature  so  much  lower 
than  that  of  the  surrounding  medium  as  to  cause  the  deposition 
of  moisture  upon  its  surface."     Mr.  Phillips  purposes  to  pursue 
the  inquiry,  with  a  view  towards  the  completion  of  the  theory  of 
this  curious   subject,  the  patient  investigation  of  which,  as  he 
justly  remarks,  cannot  fail  to  give  us  new  and  penetrating  views 
into  the  constitution  of  the  atmosphere.* 

67.  When  the  temperature  of  the  region  of  the  air  in  which 
the  resolution  of  the  cloudy  vapour  into  water  takes  place  hap- 
pens to  be  below  the  freezing  point,  the  globules,  in  the  act 

On  what  does  the  size  of  the  drops  depend  ? 

What  local  circumstances  appear  to  affect  the  quantity  of  rain  falling  on 
any  given  portion  of  the  earth's  surface? 

What  relation  appears  to  subsist  between  the  elevation  of  a  plain  and 
the  quantity  of  rain  which  falls  upon  it? 

To  what  is  the  observed  difference  attributed  ? 

*  Report  of  British  Association,  for  1833,  pp.  410  412. 


SNOW,  HAIL,  &C.  459 

of  union,  become  congealed  into  needle-shaped  or  spicular  crystals, 
which  form  little  hexagons  almost  infinitely  modified;  and  these 
again  combining  as  they  descend,  produce  flakes  of  snow.  Some- 
times the  frozen  masses  are  very  small,  constituting  sleet.  At 
other  times  they  assume  the  more  formidable  character  of  hail. 
"  Hailstones  are  often  of  considerable  dimensions,  exceeding 
sometimes  the  length  of  an  inch.  They  may,  therefore,  fall  with 
a  velocity  of  70  feet  per  second,  or  at  the  rate  of  about  50  miles  in 
the  hour.  Striking  the  ground  with  such  impetuous  force,  it  is  easy 
to  conceive  the  extensive  injury  which  a  hail-shower  may  occasion 
in  the  hotter  climates.  The  destructive  power  of  these  missiles,  in 
stripping  and  tearing  the  fruits  and  foliage,  increases,  besides,  in 
a  more  rapid  ratio  than  the  momentum,  and  maybe  estimated  by 
the  square  of  their  velocity  multiplied  into  their  mass.  This  fatal 
energy  is  hence  the  fourth  power  of  the  diameter  "of  the  hailstone."* 
68.  The  celebrated  Voha  ascribed  the  formation  of  hail  to  elec- 
tricity, and  proposed  to  defend  tracts  of  country  from  hail-storms 
by  rods  on  the  principle  of  lightning  conductors.  These  hail- 
rods  or  paragreles  as  they  were  called,  were  tried  in  France  and 
Switzerland,  but  apparently  with  little  advantage.f 

When  is  snow  instead  of  rain  the  result  of  deposition  of  vapour? 

At  what  rate  does  the  destructive  energy  of  hail-stones  increase  with 
their  diameter? 

On  what  two  principles  does  Mr.  Espy  found  his  theory  of  aqueous  de- 
positions ?  (Note.') 

*  Leslie  on  Heat  and  Moisture. 

t  For  an  account  of  a  terrific  hail-storm,  in  which  some  of  the  masses 
weighed  a  pound  each,  see  Commodore  Porter's  Letters  from  Constanti- 
nople. On  the  subject  of  rain,  hail,  snow,  and  water-spoiits,  a  very  inge- 
nious theory  has  recently  been  advanced  by  Mr.  James  P.  Espy,  who  refers 
the  occurrence  of  these  phenomena  to  the  influence  of  the  latent  heat  of 
vapour,  given  out  in  its  condensation,  acting  as  sensible  heat  on  the 
atmospheric  air,  which,  having  a  low  specific  heat,  will  be,  in  any  given 
case,  more  expanded  by  the  heat  of  the  vapour  which  has  been  condensed, 
than  it  is  contracted  by  the  diminution  of  bulk,  in  the  turning  of  that 
vapour  to  water.  This  increase  of  bulk  in  the  air  may  occur  when,  satu- 
rated with  vapour,  it  ascends  from  the  surface  of  the  earth  in  consequence 
of  the  diminution  of  its  specific  gravity — a  mixture  of  air  and  watery 
vapour  being  lighter,  bulk  for  bulk,  than  pure  atmospheric  air.  It  is  known 
that  a  mass  of  air,  saturated  with  vapour,  at  any  temperature,  will  deposit 
some  portion  of  its  vapour  on  being  suddenly  dilated  in  the  receiver  of  an 
air-pump.  In  rising  to  the  upper  regions  of  air,  the  same  result  will  be 
obtained,  and  the  more  decidedly  the  higher  it  rises,  for  the  dilatation  wiil 
be  the  greater  as  the  height  becomes  more  considerable.  But  though,  by 
the  dilatation,  the  vapour  is  condensed,  yet  the  air  which  has  parted  with 
it  does  not  contract  and  re-descend,  for  the  latent  heat  given  out  is  suffi- 
cient to  keep  its  temperature  above  what  it  would  have  been  had  the 
same  bulk  of  dry  air  been  carried  to  the  same  height  from  the  surface  of 
the  earth.  Mr.  Espy  has  found,  by  calculation,  "  that  the  quantity  of  latent 
caloric  given  out  by  the  change  of  vapour  to  water  or  cloud,  is  sufficient 
to  produce  an  expansion  in  the  air  six  times  greater  than  the  contraction 
caused  by  the  vapour  turning  to  water."  "  This  calculation  is  founded  on 
three  principles,  which  are  all  demonstrated  by  experiment.  1.  The  latent 


460  METEOROLOGY. 


Dew,  Hoar-frost,  and  Ground-ice. 

69.  The  precipitations  of  water  from  the  atmosphere,  already 
described,  depend  on  changes  of  temperature  in  the  air;  but  there 
are  others  frequently  taking  place  in  consequence  of  depression 
of  temperature  in  solid  bodies.  In  the  summer  season,  in  clear, 
calm  nights,  the  surface  of  the  earth  and  growing  plants  are  found  at 
sun-rise  covered  with  globules  of  limpid  moisture,  so  that  the  trees 
and  hedges  glitter  in  the  first  rays  of  the  sun,  as  if  they  were  hung 
with  multitudes  of  brilliant  diamonds  or  transparent  pearls.  This 
phenomenon,  so  often  described  by  poets  as  well  as  philosophers, 
and  so  familiarly  known  to  all  who  inhabit  the  country,  consti- 
tutes dew ;  which,  in  some  situations,  occurs  so  copiously  as  to 
supply  the  want  of  rain.  The  circumstances  under  which  it  is 
precipitated,  are  so  different  from  those  which  accompany  the 

What  is  meant  by  dew  ? 


heat  of  vapour  is  a  constant  quantity  equal  to  1212°  of  Fah.  2.  The  ca- 
pacity of  atmospheric  air  is  25,  that  of  water  being  100.  3.  The  expansion 
of  air  by  heat  is  l-480th  of  the  whole,  for  every  degree  of  Fah.  above  its 
bulk  at  32°." 

The  result  above  stated  leads  to  the  conclusion,  that  the  commencement 
of  condensation  in  an  ascending  current  of  air  will  cause  an  expansion  of 
the  whole  mass  of  air  above  the  cloud,  by  keeping  its  temperature  elevated, 
and  causing  it  to  rise  and  spread  out  in  every  direction  above  the  cooler 
masses  around  it. 

Air,  ascending  into  the  upper  regions  of  the  atmosphere,  is  cooled  one 
degree  for  each  100  yards  of  ascent.  By  rising  9000  yards,  therefore,  it 
would  be  cooled  90  degrees.  But  if  air,  saturated  with  vapour,  should 
ascend  to  the  same  height,  and  should  lose  even  45  degrees  of  heat,  it 
would  deposit  the  greater  part  of  its  vapour  in  consequence  of  the  rapidly 
diminished  quantity  of  that  substance  capable  of  being  suspended  in  the 
air  at  low  temperatures.  When  much  vapour  is  contained  in  the  air  at 
the  surface  of  the  earth,  the  latent  heat  from  deposition  would  be  more 
than  sufficient  to  heat  the  air  to  45°  above  the  temperature  due  to  dry  air 
at  the  same  height.  The  heated  air  will  consequently  continue  to  rise. 
The  equilibrium,  being  thus  once  disturbed,  cannot  be  restored  while  air 
highly  charged  with  vapour  exists  at  the  surface  of  the  earth.  The  pres- 
sure of  the  air,  as  indicated  by  the  barometer,  will  be  diminished  beneath 
the  cloud — and,  if  it  amount  to  one  inch,  may  cause  an  ascending  cur- 
rent of  230  feet  per  second — "  sufficient  to  carry  up  large  drops  of  rain, 
after  they  are  formed,  far  above  the  region  of  perpetual  congelation," 
where  they  may  be  frozen  and  carried  to  the  sides  of  the  ascending  cur- 
rent. When,  at  the  commencement  of  the  ascension,  "  the  dew  point  is 
very  high,  and  the  ascending  current  very  narrow,  the  upward  velocity 
will  be  very  great,  and  thus  water-spouts,  or  what  the  French  call  trombes, 
both  by  sea  and  land,  may  be  formed." 

The  author  supposes  that  "  all  the  phenomena  of  rains,  hails,  snows 
and  water-spouts,  change  of  winds  and  depressions  of  the  barometer,  fol- 
low as  easy  and  natural  corollaries  from  the  theory  here  advanced,  that 
there  is  an  expansion  of  the  air  containing  transparent  vapour,  when  that 
vapour  is  condensed  into  water"  This  theory  is  the  result  of  much  careful 
observation,  and,  as  its  author  conceives,  is  justified  by  multitudes  of  facts, 
which  meteorologists  have  not  been  able  to  solve  on  any  other  hypothesis. 
See  Trans,  of  the  Geol  Soc.  of  Penn.,  vol.  i.,  p.  342.— ED. 


HOAR-FROST.  461 

separation  of  moisture  from  the  air  in  the  state  of  rain,  that  philo- 
sophers were  long  at  a  loss  to  account  for  it.  Among  the  causes  as- 
signed for  its  production,  one  of  the  most  plausible  was  electricity. 

70.  At  length,  however.  Dr.  W.  C.  Wells,  by  an  ingeniously 
conducted  series  of  experiments,  ascertained  that  dew  is  chiefly 
owing  to  the  radiation  of  heat  from  the  substances  on  which  it  is 
deposited.     Hence  it  is  that  dew  never  forms  during  nights  which 
are  both  cloudy  and  windy  ;  and  if,  in  the  course  of  a  night,  the  wea- 
ther from  being  serene  should  become  dark  and  stormy,  the  dew 
which  may  have  been  produced  will  disappear.     Grass,  leaves  of 
vegetables,  or  other  bodies,  must  be  quite  exposed  to  the  sky  in 
order  to  enable  them  to  receive  dew ;  and  therefore  the  slightest 
shelter  will  prevent  its  deposition  on  the  covered  surface.     The 
quantity  of  dew  must  necessarily  depend,   not  entirely  on   the 
degree  of  radiation  at  any  one  time  and  place,  but  also  on  the 
amount  of  moisture  present  in  the  air.     Perfect  stillness  in  the 
atmosphere,  therefore,  is  not  always  so  favourable  to  the  deposi- 
tion as  gentle  motion  ;  by  means  of  which,  after  one  mass  of 
air  has  been  deprived  more  or  less  of  its  moisture,  by  contact  with 
radiating  bodies,  other  portions  of  air,  from  which  it  has  not  been 
separated,  may  be   successively  brought   near   to  those  bodies, 
which  may  thus  receive   repeated   deposits.     Any  considerable 
agitation,  however,  approaching  to  wind,  causes  the  precipitation 
to  cease. 

71.  These  and  many  other  circumstances,  connected  with  the 
occurrence  of  dew,  admit  of  a  complete  and  lucid  explanation,  by 
referring  them  to  the  property  of  radiation.     Light,  fibrous  sub- 
stances, as   filaments   of  gossamer,  wool,  thread,  cotton,    hair, 
grass,  and  low  plants,  both  dead  and  living,  are  among  the  best 
radiators,  and  receive  dew  most  readily  ;  while  rocks,  bare  earth, 
and  considerable  masses  of  water,  have  less  disposition  to  part 
with  their  heat  in  the  same  manner,  and  therefore  remain  free 
from  dew. 

72.  Hoar-frost  is  merely  frozen  dew,  owing  either  to  powerful 
radiation,  when  the  atmosphere  itself  has  a  temperature  above  the 
freezing  point,  but  the  radiating  substances  part  with  their  heat 
so  fast  as  to  fall  below  it,  and   thus  the  moisture  freezes  on  them 
as  soon  as  it  is  precipitated  :  or  the  congelation  may  be  accom- 
plished and  preserved  by  a  depression  of  temperature  in  the  air 
below  32°  Fahrenheit.     Glass  is  an  excellent  radiator  of  heat; 
and  hence  it  often  receives  depositions  of  hoar-frost  in  winter, 
incrusting  its  surface  sometimes  with  elegant  frost-work,  bearing 

To  what  is  the  deposition  of  dew  at  night  chiefly  attributable  ? 

What  is  necessary,  in  regard  to  the  situation  of  plants,  in  order  that  they 
should  receive  a  deposit  of  dew  ? 

What  is  the  effect  of  motion  in  the  air  on  the  quantity  of  dew  which  it 
will  deposit  ? 

What  character,  in  regard  to  emitting  heat,  have  bodies  which  accumu- 
late much  dew  ? 

Why  does  glass  accumulate  hoar  frost  ? 
2Q2 

. 


462  METEOROLOGY. 

a  fanciful  resemblance  to  trees  and  landscapes.     Some  of  the  sim- 
pler forms  of  hoar-frost  are  exhibited  in  the  following  figures. 


73.  The  trees  and  hedges  also  in  the  cold  season  display  yet 
more  beautiful  assemblages  of  snowy  crystals,  the  complicated 
figures  of  which  it  would  be  useless  to  attempt  to  trace.     Hoar- 
frost, in  the  -spring,  sometimes  destroys  the  buds  and  flowers  of 
plants,  and  literally  deprives  the  gardener  of  the  fruit  of  his  labour. 
It  had  been  long  known  that  tender  vegetables  and  opening  buds 
might  be  protected  from  its  deposition   by  a  very  slight  shelter ; 
but  it  is  only  since  the  discoveries  of  Dr.  Wells  have  been  pro- 
mulgated, that  the  manner  in  which  such  shelter  acts  (namely,  by 
preventing  radiation)  has  been  properly  understood. 

74.  The  production  of  ground-ice,  that  is,  ice  formed  at  the 
bottom  of  rivers,  is  a  phenomenon  that  has  often  attracted  the  no- 
tice of  philosophers,  and  given  rise  to  different  hypotheses.     Mr. 
T.  A,  Knight,  in  a  paper  published  in  the  Philosophical  Transac- 
tions, attributes  the  formation  of  ice  in  such  situations  to  particles 
originally  congealed  at  the  surface,  and  afterwards  carried  to  the 
bottom  by  the  eddies  of  streams.*     Neither  this  nor  other  theo- 
ries that  have  been  advanced  can  be  considered    as  satisfactory. 
The  phenomena  are  well  described   in  a  paper  by  Mr.  Richard 
Garnett,  published  in  Brande's  Journal  of  Science  in  1818;  but 
that  gentleman  does  not  propose  any  new  mode  of  accounting  for 
the  existence  of  ground-ice.   He  remarks,  however,  that  it  never 
occurs   but  under  peculiar   atmospherical   circumstances. f     He 
adds,  that  "  the  immediate  cause  of  the  formation  of  this  ice 
seems  to  be  the  rapid  diminution  of  temperature  in  the  stone  or 
gravel  in  the  bed  of  the  river,  (on  which  it  is  deposited,')  connected 
with  sudden  changes  in  the  state  of  the  atmosphere."^ 

Why  does  a  simple  veil  or  screen,  placed  over  plants,  prevent  their  de- 
struction by  frost? 

What  is  meant  by  ground-ice? 

What  attempts  have  been  made  to  explain  its  production? 

*  See  Abstracts  of  Papers  in  Philos.  ^rans.,  vol.  ii.  p.  16. 
t  Brande's  Journal,  vol.  v.,  p.  269. 
t  Idem,  p.  273. 


V 


METEORITES.  463 

5.  Experiments,  which  could  be  best  prosecuted  in  frosty 
weather,  would  be  requisite  to  develop  the  cause  of  the  formation, 
of  ground-ice.  It  may,  however,  be  not  improbably  attributed  to 
the  acquisition  by  stones  or  gravel,  in  consequence  of  radiation  of 
heat,  of  a  temperature  below  the  freezing  point,  while  the  water 
passing  over  those  substances  was  somewhat  warmer.  It  may 
be  stated,  as  an  argument  in  favour  of  this  supposition,  that  ground- 
ice  is  found  only  in  clear,  running  water,  through  which  it  may 
be  conceived  radiation  might  take  place.* 

76.  Various  other  atmospheric  phenomena  are  frequently  treated 
of  in  books  relating  to  meteorology.     These  are  chiefly  of  two 
classes,  namely,  those  which  may  be   explained  by  means   of 
the  laws  of  optics,  and  those  which  appear  to  depend  on  electro- 
magnetism.     Among  optical  or  photonomical  phenomena,  there 
are  few  more  curious  than  the  mirage,  looming,  and  the  fata 
morgana,  or  more  beautiful  than  the  rainbow  ;  and  of  these  some 
notices  will  be  found  in  the  treatise  on  Optics,  in  the  former  vo- 
lume of  this  work.     Notwithstanding  the   brilliant  discoveries 
that  have  been  made  within  the  last  forty  or  fifty  years  relative  to 
electricity,  we  are  yet  by  no  means  able  to  trace  the  full  extent 
of  its  influence  over  the  atmosphere.  That  it  is  the  cause  of  light- 
ning is,  however,  universally  admitted  ;  and  to  this  subject  the 
attention  of  the  reader  has  been  directed  in  the  treatise  on  Elec- 
tricity. 

77.  Perhaps  there  are  no  atmospheric  phenomena  more  singu- 
lar or  problemetical  than  the  descent  of  aerolites,  or  meteorites, 
as  they  have  been  termed.  The  fact  of  their  fall  was  long  doubted, 
but  at  present  seems  to  be  indisputably  ascertained.     They  all 
consist  chiefly  of  magnetic  iron,  having  a  remarkable  analogy  of 
composition.     Their  origin  is  quite  uncertain  ;  and  the  different 
explanations  of  their  appearance  that  have  been  attempted,  are, 
perhaps,  equally  improbable.     Some  suppose  them  to  have  been 
formed  in  the  air,  an  hypothesis  which  D'Aubuisson  rejects  as 
untenable  ;   others  consider  them  as  the  products  of  volcanoes  in 
the  moon,    projected   into  our    atmosphere ;    and,  according  to 
Chladni,  they  are  fragments  of  planets  which  have  burst  in  pieces 
amid  the  etherial  space. 

What  is  the  composition  of  aerolites  or  meteorites  ? 
What  hypotheses  have  been  formed  respecting  them  ? 

*  This  supposition  seems,  however,  at  variance  with  the  generally  re- 
ceived opinion,  that  water  is  but  slightly,  if  at  all,  pervious  to  radiated 
heat.— ED. 


464  METEOROLOGY. 


Works  on  Meteorology. 

So  many  of  the  subjects  connected  with  this  department  of 
science  are  still  in  an  imperfect  state,  that  no  work  which  has 
hitherto  fallen  under  our  observation  can  be  considered  as  abso- 
lutely free  from  error.  Many  detached  memoirs  and  treatises  of 
great  value  are  extant,  and  we  will  present  to  the  consideration 
of  the  reader  such  as  appear  likely  to  prove  most  satisfactory 
It  is  understood  that  the  gentleman  whose  views  of  the  causes  of 
rain,  hail,  tornadoes,  and  water-spouts  we  have  presented  in  a 
preceding  page,  is  preparing  for  the  press  a  work  on  his  favourite 
department  of  study,  in  which  those  views  will  be  carried  out 
and  applied  to  numerous  phenomena  connected  with  atmospheric 
changes. 

Daniell's  Meteorological  Essays  and  Observations. 

Dalton's  Meteorological  Observations  and  Essays.  1834. 

Leslie's  Essays  on  Heat  and  Moisture. 

Front's  Chemistry  and  Meteorology. 

Forbes  on  Meteorology,  in  the  Report  of  the  British  Association 
for  1832. 

Pouillet  Elemens  de  Phys.  et  de  Meteorologie.  2  vols. 

Meteorological  Register,  from  Observations  made  by  the  Sur- 
geons of  the  Army  at  the  Military  Posts  of  the  United  States. 
Washington.  1826. 

Nicolao  Cacciatore  de  Redigendis  ad  unicam  seriem  compara- 
bilem  Meteorologicis  ubique  Factis  Observation ibus.  Palermo. 
1832. 

Article  Hygrnmetry,  in  the  Edinburgh  Encyclopedia. 

Enclyclopedia  Metropolitana,  article  Meteorology. 

Manuel  de  Meteorologie,  par  J.  B.  Felleus.  Paris.  1833. 

Forster's  Essays  on  Meteorology. 


INDEX. 


ABYMES  DE  MYANS,           .       p 
Action  at  various  distances, 

345 
9 

c 

Acid,  ctfrbonic  

21 

perchloric, 

81 

oxiodic  

82 

bromic,     .        .        .        . 

84 

hydrofluoric,     . 
silicofluoric, 

85 
86 

muriatic,  . 

91 

hydriodic, 

93 

hydrobromic,    . 
hyponitrous, 

94 

98 

nitric,        . 

9£ 

carbonic, 

103 

prepared  for  ex- 

periments, 

105 

in  geology, 

325 

107 

mellitic,    . 

107 

eroconic,  . 

107 

hydrocyanic,     . 
boracic,     . 

113 
114 

borofluoric, 

116 

117 

silicofluoric,      . 

119 

of  phosphorus,  . 

121 

hydrophosphoric, 
of  sulphur, 

125 
126 

anhydrous  sulphuric, 
hyposulphurous, 
hyposulphuric, 
selenious  and  selenic, 

128 
128 
129 
133 

hydroselenic,    . 
sulphuric,  in  mineral  wa- 

134 

ter,        .... 

180 

arsenious, 

275 

Acids,  general  account  of,  .       6G 
terminology  of, 

,  67 

77 

metallic,   .... 

134 

Adhesiveness  of  minerals,  . 

242 

Adits,  how  driven, 

203 

Aerolites,     

463 

Aerology,  a  department  of  che- 

mistry   

11 

Affinity,  simple  elective,    . 
chemical,  defined, 

62 
26 

complex, 

63 

divellent  and  quiescent, 
Aggregation,  attraction  of, 

64 
9 

Air,  hot,  in  smelting  furnaces,  p.  223 
modifies     the    earth's    sur- 
face,         .  .  324 
atmospheric,  composition  of,     96 
gravity  of,  in  meteorology,     439 
Alkali,  volatile,  how  composed,      19 
Alcyonite,  fossil,          .         .         .  424 

Albumen, 165 

Alkalies  are  true  metallic  oxides,   67 
in  mineral  water,          .  179 
Aluminum,  compounds  of,          .115 
oxides  of,  .         .  258 

properties  of,    .         .  152 
Alumina,  in  lime  and  magnesia,    163 
Alloys,  metallic,          .         .         .230 
table  of,  .        .        .   234,  235 
Alum,  crystals  of,         .         .         .284 
Alluvial  deposits,        .        .         .  397 
fossils  in,         .  428 
Ammonia,  how  combined  with 

muriatic  acid,        .     27 
precipitates  zinc  from 

sulphuric  acid,       .     29 
properties  of,      .        .  100 
Amalgams,  ....  231 

table  of,  .  .  .  235 
Amorphous  minerals,  .  .  242 
Analcymee,  ....  262 

Anomalies  of  atomic  weights,    .     55 
Animal  substances  exhale  am- 
monia,       .        .        .  101 
fossils      in     submedial 

rocks,         .        .        .410 
kingdom,        .        .        .  168 
products,  chemical,       .  169 
matter  in  soils,       .        .  176 
how       different 
from  vegetable,     69 
Animals  introduced  into  mines,    194 
Antimony,  binary  compounds  of,  137 
properties  of,     .         .140 
native,       .        .        .  250 
Antimonic  oxide,        .        .        .  268 
Ynthracite,          ....  251 
Anthropophyllum,       .        .        .  425 
Anthropolites,      .         .         .         .432 
Analysis,  meaning  of,         .        .  160 
of  vegetables,      .        .167 
of  soils,        .        .        .172 
Anticlinal  axis    ....  389 
465 


466 


INDEX. 


Apparatus  for  decomposing  wa- 
ter,        .        .       p. 


90 


for  burning  diamonds,  104 
Hare's,  for  boron,          115 

Apophyllite 262 

Aral  lake,  level  of.     .        .        .  32 
Arrangement  of  bodies,  chemical,  15 
Arborizations,  metallic,       .        .     45 
on  glass,        .        .     46 

Arbor  Dianae 45 

Arragonite,          ....  271 


Arsenic,  binary  compounds  of, 
properties  of, 
localities  of, 
compounds  of, 
Arsenious  acid,   . 
Art  of  mining,     . 
Artesian  wells,  temperature  in, 
Asparagin,  . 

Aspiration,  winds,  caused  by,     . 
Assays,  mechanical,   . 

by  the  dry  method, 
in  the  moist  way,  . 
Attraction,  two  species  of, 
chemical,  . 

laws  of, 

electric,  affects  che- 
mical combination, 
Atmosphere,  temperature  of, 

action   of,   on    the 

earth, 

Atmospherical  phenomena, 
Atom,  chemical  meaning  of, 
Atomic  weights,  how  expressed, 
must  be  found- 
ed on  analy- 
sis, 

Aubert's  experiments  on  sponta- 
neous combustion,  . 
Aurum  musivum, 
Auriferous  silver, 
Avalanches,  effects  of, 
Aventurine, 


137 
139 


.  196 
.  250 
.  275 
.  19G 
313 
1G4 


209 

210 

213 

9 

26 
27 

43 
315 

331 


Bergmann's  error  explained,  p.  63 
Berthollet  on  decomposition,  63 
Bertholi,  spontaneous  combus 

tionof,     .  50 

Berzelius'  atomic  weights,  56 

view    of   all    natura 

compounds,      .  69 

procured  silicon,  116 

classifications  of  bodies,136 
discovered  thorinum,     153 
system  of  mineralogy,    244 
Beudant's  classification  of  mine- 
rals, 245, 


Beithraupt  on  pearly  lustre, 
Binary  compounds  of  metals, 

Birdlime 

Bittern  the  source  of  bromine, 
Bihydroguret  of  phosphorus, 
Bisulphuret  of  hydrogen,    . 


440  Bismuth,  compounds  of, 


.  245 
239 
137 
166 

83 
125 
130 
155 
158 
195 
248 
254 
25" 
165 
431 

64 
102 
252 
375 

438  Blowpipe,  action  of,  .  .211,  212 
52, Body,  human,  combustible  ma- 


properties  of, 
localities  of, 
native, 
sulphuret  of, 
oxide  of, 

Bitter  principle, 

Bize  bone  caverns, 

Black's  diagram  of  affinity, 

Black,  ivory,       . 

Blende,        .... 

Blocks,  erratic, 


56 


Axinite 267 

Azote,  properties  of,   .        .  .     18 

Bagnes,  lake  of,  burst,        .  .  242 
Baku,  fine  temples  at, 

Balsams, 166 

Baryum,  compounds  of,      .  .  145 

properties  of,         .  .  149 

Barometric  height  at  London, 

Barytes,  bromate  of,            .  .     84 

native  sulphate  of,  .  278 

Bases,  double,     .                 .  .     66 

chemical,                   .  .     67 

Basin  shaped  strata,            .  .  388 

Basilosaurus,       .                 .  .  426 

Basalt,          .        .  .  384 

Bergmann  on  decompositions,  .    62 


te rials  in 51 

Bodies,  simple,  .  ,  .  .69 
Bohon  upas,  ....  326 
Boulders,  whence  derived,  .  375 
Books  on  chemistry,  .  .  .  185 
metallurgy,  .  235 

mineralogy,  .  .  282 
crystallography,  .  .  297 
geology,  .  .  .397 
oryctology,  .  .  435 

meteorology,        .        .  464 
Bone  caverns,      ....  428 
Bones  human  in  caverns,   .        .     31 
Boron,          .        .        .        .        .113 
binary  compounds  of,      .     72 
fluorides  of,       .        .        .     87 
chlorides  of,  .         .116 

Boracic  acid  in  mineral  water,      180 

439  Borates, 270 

Bovey  coal 401 

Bovista  giganteum,     .        .        .31 
Brocken,  section  of  the,      .         .  392 
Brohlthal,  carbonic  acid  of,        .  326 
Bromine,  nature  of,     .        .        .     23 
properties  of,       .        .     83 
compounds  of,      .        .     83 
atomic  weight  of,        .    85 


INDEX. 


467 


Brewster  on  ignition  of  pJatina,  p.  37 
Bromide  of  sulphur,  .  .  .  131 
Bubbles,  soap,  thickness  of  their 

film,         .        .        .        .        .31 
Butter  of  antimony,     .        .        .  144 

Cadmium,  binary  compounds  of,  154 


properties  of, 

Calcium 

fluorides  of, . 
chloride  of, 
compounds  of, 
properties  of, 
Calcining  furnace, 
Calcareous  spar, 

rocks  formed  under 
the  sea, 

Camphor, 

Candescent  state  of  the  earth,    . 

Caoutchouc,        . 

Carbon,  combining  volume  of,  . 

binary  compounds  of,    . 

particular  properties  of, 

conducts  electricity,     . 


Celestine 

Cemeteries    of   Dunwich    sul 

merged,    .... 
Cerium,  binary  compounds  of, 


Cerite, 


properties  of, 


Cerithium  giganteum, 
Cementation, 
Chamisso  on  corals,    . 


85  Chamelion  mineral, 
131  Charcoal,  spontaneous   combus- 
145|     tion  of,      . 


>.277 

.  350 
.  154 
.  157 
.  261 
.  426 
.  224 
.  355 
.  143 


35 


150  Changes  of  the  earth's  surface,     369 
hange  of  properties  by  combi- 


272 

354 
166 
299 
166 
58 
71 
101 
102 
108 
109 
131 
21 


electricity 
protochloride  of,    . 
iodide  of,       . 
sulphuret  of, 
found  separate, 
and  carburets,  as  mine- 
rals,  .        .        .        .250 
Carbonates  decompose  insoluble 

salts,     ;         .        .66 
in  mineral  waters,   .  179 
mineral,    .         .         .  271 
isomorphic,       .        .  286 
Carbonic  acid  in  the  atmosphere,    96 
properties  of,        .  103 
in  mineral  waters,  177 
in  the  earth,          .  325 
11 
110 


Carbo-hydrogen,  Faraday's, 
Carburet  of  hydrogen, 
Carbonate  of  lime,  precipitated 

from  lakes,    . 
of  soda,     .         .        .  353 
Carbonaceous   matter   in    fossil 


Carboniferous  group,  .  .  .  394 
Carnivorous  animals,  in  bone 

caverns, 42£ 

Carrara  marble,  .        .        .  27S 

Cafmine,  colouring  power  of,  .  31 
Caspian  sea,  level  of,  .  .  322 
Cassini  on  the  temperature  of 


nation,  ....     12 

"hemistry  defined,      ...       9 
science  of,  how  com- 

pleted,  .        .        .13 
Chemical  action  in  combustion 

and  respiration,      .     13 
attraction,  laws  of,   27,  28 
.  463 
.    83 
.  159 

native,  .  .  .  280 
as  primary  compounds,  67 
of  potassa  " 

oxygen,  . 
of  nitrogen, 
cobalt,  . 
bromine,  . 
sulphur,  . 
aluminum, 


Chladni's  theory  of  aerolites, 
Chloridic  acid,    . 
Chlorides  of  mercury 


Chloride 


furnishes 

74 
99 
143 
85 
131 
152 
20 
20 

20, 78 

ydrate  of,   .         .         .     81 
binary  compounds  of,       70 
with  hydrogen,   .         .     92 
Chloropheite,      .        .        .        .261 


Chlorine  supports  combustion, 
used  in  bleaching, 
properties  of, 
h\ 


Chromates, 


Chrome,  binary  compounds  of, 

properties  of, 

localities  of, 
Cipolin, 


269,  270 


138 
141 
196 
273 
stems, 416  Circumstances  influence  affinity,  61 


Cirrus  cloud, 

Clues  Mary,  spontaneous   com- 
bustion of,        .... 

Claromont,  spontaneous  combus 
tion  described  by,   . 

Classification  of  metals, 

of  minerals,  . 

[Cleavage  of  crystals, 


the  earth,         ....  309 

Cassius,  powder  of,     .         .        .  144|Climate  of  the  oolitic  period, 
Cast  iron,  kinds  of,  .         .  224;Clouds,  remarks  on, 

Casts  of  medals  from  mineral  de-  formation  of,  . 

posits, 273 1  height  of, 

Cawk,  a  mineral  gangue,  .        .  190|  constitution  of, 

Cavendish  discovered  hydrogen,    87i  modifications  of 


454 

48 

50 
136 
244 
289 
419 
450 
451 
452 
453 
453 


468 


INDEX. 


Cloud  of  day,      .        .        .       o.  455 
of  night,    .        .        .         .456 
Coal,    ....                   282 

Copper,  protected  from  corrosion 
by  zinc,     .        .        p.  44 
binary  compounds  of,  .  154 
properties  of,        .        .  158 
localities  of,  .         .         .194 
analysis  of,    .         .         .  214 
ores,  reduction  of,         .  226 
alloys  of,        ...  233 
native,  ....  247 
sulphurets  of,         .        .  253 
native  oxides  of,   .        .  257 
carbonate  of,      .  275 
phosphate  of,     .  276 
Coral  reefs,  formation  of,   .        .  355 
Cornelian,   260 
Uornean,      384 
Cordier  on  the  temperature  of 
the  earth,         ....  310 
Cosmogony,  system  of,         .         .  298 
Cotton,  chemical  nature  of,        .  166 
Cretaceous  group,        .         .         .  390 
Dri  d'etain,          ....  144 
Crinoidal  fossil  animals,     .        .411 
^roconic  acid,     ....  107 
Cross  courses,      ....  192 

measures,  fossils  in,    .         .  4K 
Bovey,         ....  401 
Cobalt,  binary  compounds  of,    .  13i 
properties  of,  .        .        .  143 
chloride  of,     .        .         .143 
localities  of,    .         .         .195 
Cobalt,  sulphurets  of,          .        .  253 
glance,    .         .         .         .256 
oxides  of,         ...  257 
arseniates  of,           .        .  275 
Codfish,  spawn  of,               .        .     32 
Coins  impressed  on  plastic  sul- 
phur,          126 
Colours,   vegetable,  affected  by 
charcoal,    .  „    .        .132 
of  minerals,    .        .        .  238 
Colum  bates,        ....  268 
Columbium,  binary  compounds 
-of,         .        .        .  137 
properties  of,   .        .  140 
Colebrook's  theory  of  the  earth's 
density,    306 

Columnar  rocks, 

Comet,  Encke's,  retarded  by  the 


390 


ether, 
Composition,  attraction  of, 

molecular, 

Combining  numbers  of  salts, 
Combustion,  a  chemical  process, 
supported  by  iodine, 
facts  relating  to,     . 
spontaneous,    . 
spontaneous,  of  the 

human  body,  38.  48.  50 
supported    by  oxy- 


Cryptogamic    plants,   seeds    of, 
transported  through  the  air, 


316  Crystals,  various  forms  of, 


simple, 
in  fossils, 
Crystallography,  purpose  of, 


331 

242 
290 
405 
283 


1 3  "  works  relating  to,  297 

23  Cumulus  cloud,  .        .        .  455 

34  Cumulostratus 457 

35  Cupellation,         .        .        .        .217 
Cuvier's  discoveries  in   orycto- 

logy, 302 

Cyanogen,  .         .         .         .         .112 


gen, 


Como,  lake  of,  filled  by  detritus,  344 
Compounds  differ  f^om  their  con- 
stituents,      .        .     26 
of  gases  become  so- 
lids,      ...     27 
primary  and  second- 
ary 


75  Daniell's  melting  point  of  silver,  135 
illustration  of  the  dew- 
point,         .        .        .  449 
|  Davy's  method  of  protecting  cop- 
per,       .  .45 


66 


safety  lamp, 
Days,  length  of  the,  affected  by 


110 


of  metallic  elements,  144; 


the  cooling  of  the  earth,         ".312 

Datolite, 271 

Compression  of  carbonic  acid,    .  106jDiallage  rock,     .  .        .  382 

of  the  earth  at  the         |  Dichroite, 265 

poles, 


Compressibility  of  air  and  water,  307 
Condor  of  the  Andes, 
Conductors  and  non-conductors 

of  electricity, 
Conformable  rocks, 
Consistency  of  minerals, 
Continents,  elevation  of, 
Contortions  of  strata,  . 
Copper,  dissolved  by  sulphuric 
acid, 


307 
438 

25 

387 
241 
378 
386 

28 

Dip  of  strata,       ....  389 
Discoveries  of  modern  philoso- 
phers,            13 
Districts,  mining,  why  barren,   .  198 
Disthene,     261 
Diamond,  an  isolated  body,        .     14 
chemical  nature  of,     .  102 
apparatus  for  combus- 
tion of,     .        .        .104 
variable  hardness  in,  .  240 

INDEX. 


469 


Diamond,  remarkable  specimens 

Elements,  four,  of  the  ancients,  p.  15 

of,    .p.  250 

seven,  of  the   alchy- 

Divisibility    of   matter    and    of 

mists,       .        .        .15 

*                                         t\f* 

sixty-four  of  the   mo- 

Deads in  mineral  veins,     .        .  189 

derns,      .         .         .15 

Decomposition,  double,       .        .     64 

metallic  and  non-me- 

Deinotherium,    ....  428 

tallic,                        .     1G 

Density,  a  means  of  distinguish- 
ing bodies,         .         .14 

list  of,  -      .         ,        .18 
Elie  de  Beaumont  on  mountains,  319 

in  minerals,     .        .        .  241 

Encke's  comet,  how  retarded,    .  316 

Denudation  of  surfaces,      .        .  373 

Encrinites,  399 

Depth  of  mineral  veins,      .         .  189 
Deposits,  alluvial,        .         .         .  428 

Epsom  salts,  crystals  of,      .         .  284 
Epidote  in  mineralogy,        .         .  264 

Dew,  theory  of,  .         .         .         .  461 

Equivalents,  chemical  scale  of,       57 

Dew-point,  nature  of  the,  .        .  449 

Erie,  lake,  may  be  emptied,  337.  342 

method  of  ascertaining,  450 

Erratic  blocks,     ....  375 

Docimasy,   .....  209 

Eruptions  and  earthquakes,        .  358 

Doebereiner's     discoveries     on 

Espy  on  hail-storms  and  torna- 

spongy platina,         .         .         .36 

dos,           .         .         .        .        .459 

Dolomieu  on  carbonic  acid,        .  325 

Etesian  wind,      ....  445 

Drusy  cavities,    ....  408 

Expansion,  rate  of,  in  moisture,  .  446 

Dulong  on  decomposition,  .        .     66 

Dunwich  cliffs,  degradation  of,     349 

Farquharson's  account  of  a  flood 

Dyke,  in  geology,        .        .        .  389 

in  the  Don  339 

Fault  in  rocks,     ....  389 

Earfh,  figure  of,  .        .        .        .304 
mean  density  of,       .         .  306 

Faraday  reduced  gases  to  liquids,    10 
Feldspar,      ....    262,  263 

temperature  of,        .        .  308 

Fermentation,      ....  170 

consolidation  of,  from  fu- 

Ferns, fossil,        .        .        .  403.  418 

sion,       .         .        .        .311 

Fibrous  hygrometers,                   .  447 

Earthquakes,  geological  effects  of,  357'  Fibrin,     *~  165 

frequency  of,           .  358;  Final's  cave,      ....  390 
in  Chili,         .           359  Fire-damp  109 

Earths  are  metallic  oxides,        .    67 

Fire  of,  oxidation  and  reduction,  212 

analysis  of,               .        .  161 

Flint,   260 

primary,  in  minerals,      .  161 

Floatage,  power  of,  in  the  air,    .  332 

Echinite,     424 

Flowers  of  sulphur,     .        .        .126 

Electricity,  chemical  effects  of,      40 

fossil  404 

by  evaporation   and 

Fluate  of  alumina  and  soda,  na- 

. ,                    solution,        .        .     4] 

tive  280 

opposite  states  of,  in 

Fluorine,  general  account  of,     .     23 

combining  bodies,    47 
the  cause  of  combus- 

particular properties  of,  85 
Fluor  spar,           .        .        .        .85 

tion,        .        .        .47 

crystalline  forms  of,     292 

in  spontaneous  com- 

Fluoride of  silver,       ...     86 

bustion  of  the  hu- 

ofboroni       ...     87 

man  body,     .        .     47 

Fluorides,  native,        .        .        .  279 

of  minerals,     .        .  241 

Fontinelle  on  spontaneous  com- 

Electric light  from  animals,       .    48 

bustion  50 

action   on   the    earth's 

Forms  of  bodies  classed,     .        .     10 

surface,      .        .        .368 

Formations,  general  view  of,     .  322 

Electro-positive  bodies,  with  hy- 

Fourier on  the  temperature   of 

drogen,             .         .        .         .94 

celestial  spaces,       .        .        .  317 

Electro-chemical  relations  of  mi- 

Fossil flowers,     ....  404 

nerals,      24£ 

vegetables,  sections  of,     .  417 

Electro-positive  native  metals,      246 

shells,        .        .        .        .417 

Electro-negative  metals,     .         .  249 

theorv  of,                .  299 

Elephant,  fossil,  in  Russia,         .  429  Franklin's  discovery  on   north- 

Elevation  of  mountains,      .        .  373 

east  storms,       .         .                  .  441 

of  chalk  strata,   .         .  378 

Freind's  remarks  on  crystals,     .  284 

2R 

470 


INDEX. 


Fuel  for  smelting, 
Fundamental  rocks, 
Furnace,  calcining,     . 
Fusion,  igneous,  of  the  earth, 


Gahn's  blowpipe, 

Galena,        .... 

Garnet,  family  of  minerals, 

Gases  combined  by  electricity, 
atomic  constitution  of, 
evolved  from  volcanos, 


p.  222,  223jGrenier,  mount,  fall  of,       .      p.  344 
.  387iGrenough  on  elevation  of  conti- 

226      nents, 379 

318  Greenstone  rock,        .        .        .  382 
Groups  of  formations,  .         .320 

21 1  synoptical  arrangement  of,  393 

254  carboniferous,  .        .        .  393 

264  penean,     .        .        .        .394 

40  keupric,    ....  395 

91  liasic,         .         .         .         .  394 


328 


inflammable  from  fisssures 

in  the  earth,          .        .  329 

Gas,  intoxicating,         .         .         .97 

olefiant,         .         .         .         .111 


Gangue  of  minerals, 


190 


Gay  Lussac's  instantaneous  light,   37 
on  combining  volumes,  58 

Gehlenite, 265 

Gelatin,  characters  of,         .         .  165 
Gensanne  on  the  heat  of  mines,   310 
Geognostic  epochs,      .         .         .  406 
Geology,  purpose  of,   .         .         .  298 
of  the  United  States,     .  433 
Geological  Society,  influence  of,  301 
arrangement  of  mine- 
rals and  fossils,      .  405 
Geysers  contain  silica,        .        .118 
temperature  of,      .        .  313 
deposit  of,      .         .         .  351 
Giant's  causeway,       .         .    "     .  390 
Gilding,  water,    ....  230 
Glacial  phosphoric  acid,     .        .122 
Glass,  etching  on,  by  fluoric  acid,    86 
composition  of,          .        .118 
Glance  cobalt,     ....  256 
Glauber's  salt,  crystals  of,  .        .  284 
Glucinum,  binary  compounds  of,  145 
properties  of,     .        .153 

Gluten, 165 

.  14 
.  31 
.  83 
.  155 
.  159 


Ground-ice, 
Gum, 


462 
164 
166 


Gun-barrel  for  decomposing  water,  90 
Gypsum,  deposits  of,  . 

Hading  of  mineral  veins,   . 
Hair  hygrometer,  imperfect, 
Hail-stones,  momentum  of, 
Hail-storms,  theory  of, 
Hardness  of  minerals, 


Haiiy,  simple  forms  discovered  by,  290 
Haiiy's  system  of  mineralogy,  .  244 
researches  in  crystallo- 
graphy, .  .  .288 
theory,  objections  to,  .  293 
Haworih,  mud  deluge  at,  .  .  346 
Hay-ricks,  combustion  of,  .  .  36 
Heat,  expansive  power  of,  .  9 
evolved  by  burning  bodies,  33 
and  light  in  combustion,  .  76 
of  the  earth,  Fourier  on,  .  317 


Gold,  an  isolated  body, 
malleability  of,  . 
acted  on  by  iodic  acid, 
binary  compounds  of, 
chemical  nature  of, 


test  of,        .....  213 
native,        ....  249 
localities  of,        .        .        .193 
Goniometers,       ....  295 
Gossan,  in  mineral  veins,   .         .  202 
Granite,  disintegration  of.  by 

air,      .        .        .  327.  336 

variable  characters  of,     381 

supposed  universal,       .  392 

Gravities,  specific,  of  gasses  and 

vapours,     .-  60 
of  iodine,       .     82 

Graphite, 251 

Grauwacke,        ....  383 
Great  Staple  Tor,        .        .        .327 


.  353 

188 
448 
459 
460 
409 

Hare's  mode  of  procuring  boron,  114 
Harmotome  mineral,  .  .  262 


Harmattan  wind, 


445 


Heaving  of  mineral  veins, 


191 


Henry,  Prof.,  on  Niagara  gorge,  337 
Hisingerite,         ....  261 

Hoar-frost, 461 

Horn iomorph ism,  .  .  .  287 
Homberg's  sedative  salt,  .  .  113 
Hornstone  mineral,  .  .  .  259 
Horsburgh  on  descending  cur- 
rents of  air,  .  .  .  .  442 
Hot  air  blast,  how  applied,  .  223 
Howard's  classification  of  clouds,  454 
Human  body,  combustion  of,  .  38 
bones,  fossil,  .  .  .  354 
Hurricanes,  geological  effects  of,  334 
Hutton's  theory  of  the  earth,  .  300 
of  coal  formations,  413 
81 
19 
37 
54 
55 
59 


Hydrate  of  chlorine, 
Hydrogen,  general  account  of, 


reacts  with  platina, 

and  sulphur, 

atomic  weight  of, 

volume  of, 

binary  compounds  of,    76 

peculiar  properties  of,   87 

mode  of  obtaining,    .    87 


INDEX                                                     471 

Hydrogen,  protoxide  of,      .        p.  88 
fas  ffGncrator    •        •     89 

ron,  cast  and  wrought,       .       p.  224 
native,          ....  247 

eutoxide  ol',      .        .     91 

native,  oxides  of,          .         .  256 

employed  to  inflame 

tungstate  of,         ...  269 

diamond,        .        .105 

native,  carbonates  of,  .        .  274 

phosphuretted,  .        .  124 

oxalate  of,     .        .        .        .  281 

sulphuretted,     .        .  129 

Islands  produced  by  submarine 

in  water,    .        .        .178 

volcanos,-  .         .        .  366 

bisulphuret  of,  .        .130 

destruction  of,        .        .  349 

Hydrofluoric  acid,       ...    94 

'somerism,  123 

Hydrochloric  acid,      .        .        .91 

Isomorphism,       .        .        .        .123 

Hydrobromic  acid,      .        .        .94 

Hydrochloride  of  carbon,   .         .111 
Hydrothionic  acid,      .        .        .  129 

Jasper,  varieties  of,     .        .        .  260 
Junction,  line  of,  in  strata,         .  434 

Hydroselenic  acid,      .        .        .  134 

Hydriodic  acid  93 

Kamsin  wind,     ....  445 

Hygrometry,       ....  446 

Keupric  group  of  rocks,      .        .  395 

Hygroscopes,       ....  447 
Hylffiosaurus,      ....  423 

Kibble  in  a  mine  shaft,       .        .  204 
Kirkdale  bone  caverns,       .        .  430 

Hyponitrous  acid,        .        .        .98 

Kremnitz  mine  described,          .  200 

Hypophosphorous  acid,       .        .  122 
Hyposulphurous  acid,        .         .  126 

Krokydalite,        .        .        .        .264 

Hyposulphuric  acid,   .        .         .  12£ 

Lampblack,  nature  of,        .        .  102 

Land  and  water,  relative  extent 

Ice,  ground,         ....  462 

of,     ....                .  319 

melted  in  ammoniacal  gas,     101 

Landslips,  how  caused,               .  344 

Ichthyosaurus,     ....  422 

Lapis  lazuli,        .        .                 .  266 

Igneous  origin  of  rocks,      .        .  40£ 

Latiolite,     ...                 .  266 

Impulsion,  winds  caused  by,      .  44C 

Lauder's  account  of  the  Moray 

Incompatible  salts,      .        .        .  184 

deluge,     ...                 .  338 

Increments  of  crystals,        .        .  28i 

Laumontite,         .        .                 .  262 

Intoxicating  gas,          .         ,        .97 
Indigo,  chemical  nature  of,        .  l&l 
Inulin,          164 

Lava  cut  through  by  water,       .  336 
Lavoisier  on  composition  of  acids;   66 
Laws  of  chemical  attraction,      .    27 

Instruments  for  analysis,     .        .175 
Iodine,  general  nature  of,   .        .     2J 

Lead  tree,    46 
oxides  of,     .        .        .        .55 

binary  compounds  of,     .     7] 
peculiar  properties  of,     .     81 

binary  compounds  of,         .  154 
chemical  properties  of,       .  158 

solution  of,  in  water,       .      I 

localities  of,        ...  194 

compounds  of,  with  chlo- 

effect of,  in  alloys,      .         .  233 

rine,     .        .        .        .81 
lodic  acid,  82 

sulphurets  of,      .        .        .  254 
native  oxides  of,          .        .  257 

Iodide  of  nitrogen,     .        .        .  10( 

carbonates  of,          .  274 

carbon,         .        .        .109 

arseniate  of,     .        .  275 

phosphorus,          .        .  1& 

Leaves,  fossil,     ....  402 

Iridium,  binary  compounds  of,    .  15( 

Lehman's  division  of  rock 

properties  of,        .        .  16( 

strata  300,  391 

Iron  precipitates  copper  from  so- 
lution,      .        .        .        .28 
protected  from  corrosion  by 

Leibnitz'  theory  of  the  earth,     .  299 
Lemery's  remarks  on  crystals,   .  285 
Lepidodendron,  .        .        .*•-'.  418 

zinc,          .        .        .        .4' 

Leslie  on  compressibility  of  mat- 

wire, burnt  in  oxygen  gas,       7J 

ter,  307 

binary  compounds  of,             Ifr 

Lias  rock,    383 

properties  of,        .        .           156 

Liasic  group,       ....  395 

how   detected    in    minera 

Light  in  combustion,  whence  de- 

analyses, .        .        .           162 

rived,       76 

in  mineral  water,         .           18C 

Liquor,  silicum,  .         .         .         .118 

localities  of,          .        .           195 

Lisbon,  earthquake  at,        .        .  359 

assay  of,  in  the  moist  way,     214 
ores,  reduction  of,        .        .  221 

Lithium,  binary  compounds  of,     145 
properties  of,        .        .  148 

472 


INDEX. 


Lily  encrinite,     . 
Lime,  precipitation  by, 
properties  of, 


p.  419]Metals,  native,  phosphates  of,  p.  276 
.    29  sulphates  of,       .  279 

.  150 1 Metallic  salts,  how  decomposed,     46 


how  separated  from  baryta,  164  1                acids,     ....  134 
in  mineral  waters,   .        .  181  [Metamerism,       ....  123 

native,  sulphate  of,  .        .  278 

Metallurgy,          .         .         .         .186 

secreted  by  corals,   .        .  357 

books  on,          .        .  235 

Limestone,  mountain,  fossils  in,    413 

Metallursric  chemistry,                •  214 

Lode  of  a  mine,  .        .        .        .  202  Meteoric  stones,         ".'       .        .247 

Lustre  of  minerals,      .        .        .  239 

Meteorology,  definition  of,          .  436 

Lybian  desert,  sands,  moveable 

works  on,       .        .  464 

in,     ...        .        .        .333 

Meudon  crocodile,      .        .        .  425 

Lycopodium,  section  of,      .        .  418 

Micaceous  minerals,  .        .        .  263 

Mines,         186 

Maclure's  view  of  the  geology 

depth  of,  .         .        .        .  205 

of  America,      ....  434 

Mineralogy,  objects  of,       .        .  236 

Madrepores,         .        .         .         -400 

works  on,        .        .  282 

Madreporite,        ....  412 

Mineral  kingdom,  ingredients  in,    69 

Manganese,  oxide  of,          .     74,  266 

chameleon,    .        .        .  143 

with   salt   produces 

deposits,         .        .        .  186 

chlorine,       .        .     78 

veins  188 

binary  compounds  of,  139 

waters,  ....  176 

properties  of,   .        .  142 
•     localities  of,     .        .196 

ingredients  in,    .  177 
analysis  of,         .  178 

Mantell's  discoveries  of  fossils,    376 

Minerals,  assaying  of,         .        .  209 

Magnesia,  aluminate  of,     .         .  258 

how  distinguished,     .  237 

native  carbonate  of,  .  274 

physical  characters  of,  238 

sulphate  of,        .        .  278 

constituents  of,    .        .  243 

Magnesium,  compounds  of,        .  145 

classification  of,  .         .  244 

properties  of,    .         .151 

classes  of,     .         .         .246 

Marbles,      272 

composing  rocks,        .  380 

Maskeleyne  on  the  earth's  den- 

artificially formed,      .  408 

sity,          306 

Mining,  art  of,     .        .        .        .196 

Matrix  of  a  mineral,  .         .         .  190 

system  of,  in  South  Ame- 

Matter, divisibility  of,         .       30,  31 
Mechanical  mixture,           .         .     11 

rica,     .        .        .        .201 
Minuteness  of  molecules,   .         .     29 

Medial  rocks,      .        .         .  394,  412 

Mississippi,  cut  offs  in  the,          .  347 

Megalonyx,          ....  424 

Mitscherlich  on  isomorphism,    .  286 

Megatherium,      ....  431 

Mixture,  mechanical,          .         .     12 

Mellate  of  alumina,    .        .        .  281 

effect  of,  on  compound 

Mellitic  acid  107 

bodies,       .        .        .61 

Menachan  ore,    ....  268 

Moisture  in  the  air,  by  what  in- 

Melting-pots, for  zinc  ore,  .        .  229 

fluenced,  ...     96 

Melting-point  of  metals,     .        .  135 

quantity  of,  in   the 

of  potassium,        .  146 

air,     .         .         .  446,  450 

Mercury,  affected    by  tempera- 

Moh's improvement  in  crystallo- 

tures,      .         .        .     38 

graphy,          .         .        .296 

binary  compounds  of,     155 

Molecules,  minuteness  of,  .        .     29 

properties  of,        .         .  159 

of  lead,  weight  of,     .     33 

localities  of,         .         .  194 

self-repulsive,    .         .     59 

ores  of,  how  reduced,    220 

Molybdenum,  binary  compounds 

native,         .         .         .  248 

of,      .        .        .  138 

sulphnret  of,        .         .  254 

properties  of,        .  141 

Metals,  great  variety  of,     .        .     24 

Molybdates,         .        .        .        .269 

extensive  use  of,     .        .     25 

Monas  gelatinosa,       .        .             32 

electro-negative,  not.  cor- 

Moray, deluge  at,        .        ,         .  338 

roded,  .        .        .        .44 

melting-point  of,     .         .  135 
three  classes  of,       .         .  136 

Motion,  rotatory  of  the  earth,     .  312 
Monsoons,  how  explained,         .  444 

in  primordial  rocks,        .  408 

Mountain  limestone,  .      *!T       .  399 

INDEX. 


473 


Mountains,  height  of,  compared 
with    the     earth's 
diameter,       .       p.  320 
volcanic,  .        .        .361 
elevation  of,     .        .  373 


Ore,  silver,  how  reduced,   .       p.  218 
Ores  of  lead,  assayed  in  the  hu- 
mid way,         .         .         .  214 
of  gold,  reduction  of,     216,  217 
of  zinc,  reduced,        .        .  229 


Mud,  deluge  of,  .         .        .        .346 
Multiples  in  combining  atoms,  .     53 
Muriatic  acid,     .        .        .        .91 
in  mineral  waters,  180 
Muriates  in  mineral  waters,  182,  183 

Naphthaline,       .        .        .        .111 
Native  iron,         ....  247 
Naumann's    views    of    mineral 
forms  296 
Navir,  grind  of  the,     .        .        .348 
Neptunists,          .        .        .        .301 
Neufchatel,  lake,  described   by 
Saussure,          .        .        .        .343 
Neutral  primary  compounds,    66.  68 
New  Jersey,  denudations  in,      .  377 
Niagara,  detrition  at,          .        .  336 
falling  of  rocks  at,         .  342 
Nickel,  compounds  of,        .        .154 
properties  of,  .        .        .157 
localities  of,    .        .        .  196 
copper,    ....  247 
sulphurets  of,          .        .  253 
Nimbus,      457 
Nitrates,       277 

Organo-chemical  substances, 
Organic  remains  in  the  United 
States,           . 
Oryctology,  purpose  of, 
works  on, 
Osseous  breccias 
Outlying  rocks, 
Oxalate  of  iron, 
Oxalic  acid, 
Oxacids,       .                  . 
Oxides,  metallic, 
and  acids, 
of  chlorine, 
of    electro-positive    me- 
tals,    . 
Oxide,  nitrous,     .... 
carbonic,  . 
of  phosphorus,  . 
Oxygen,  general  account  of, 
evolved  at  the  positive 
pole,  .... 
combining  weight  of,  . 
mode  of  generating, 
peculiar  properties  of  . 
absorbed  by  melted  sil- 
ver,   . 
combinations    of,   with 
sulphur, 
binary  compounds  of,   . 

Palladium,    binary    compounds 
of,         . 
properties  of,    . 
Panean  group,     . 
Particles,  magnitude  of, 
Paragreles  of  Volta,    . 
Paris  observatory,  caves  of  the, 
Palseotherium  maximum,    . 
Peacock,  Mrs.,  combustion  of,    . 
Pechblende,        . 
Pelissy's  theory  of  fossils,  . 
Penzance  mine, 
Pentremites,        . 

281 

433 
398 
435 
431 

389 
281 
107 
67 
25 
77 
80 

256 
98 
103 
120 
18 

42 
53 
73 
74 

218 

126 
156 

155 
160 
394 
9 
459 
309 
427 
49 
257 
299 
206 
411 
420 

10 

128 
406 
208 
80 
232 
27* 

Nitre,  crystalline  form  of,  .        .  285 
Nitrogen,  general  account  of,     .     18 
the  base  of  nitric  acid,    18 
combines  with  oxygen,     53 
binary  compounds  of,      71 
particular  properties  of,  95 
compounds    of,    with 
oxygen,    .         .         .96 
protoxide  of,        .        .     97 
chloride  of,          .        .     99 
Nitrous  acid,       .        .        .        .98 
Nodules  in  geology,    .         .         .  391 
Nomenclature  of  acids  and  salts,    77 
Notch  in  the  White  mountains,    342 
Nucleus,  primary,  of  crystals,    .  288 

Ocean,  bottom  of,  how  shaped,     319 
Octaedrons    from    cubic    mole- 
cules,          294 
Ochre,  uran,        .        .        .        .257 
Oil  of  heaven,     .        .        .         .168 
Oils,  fixed  and  volatile,      .        .     65 
Old  women,  combustion  of,        .     51 
Olefiantgas,        .        .        .        .111 
Oolite,          273 

Pentacrinite,  Briarean, 
Permanent  gases  reduced  to  li- 
quids,      .         .        .        . 
Perchloride  of  phosphorus, 
Periods,  geological,     . 
Persian  process  for  silver,  . 
Peroxide  of  chlorine, 
Pewter,  composition  of, 
Phosphates,  native,     .        . 
Phosphorus,  general  account  ^r 
combustio^ 

Oolitic  group,  fossils  in, 
Opal,    
Ore  veins  of,  how  discovered, 
silver  how  assayed,  . 

.  419 
.  260 
.  197 
.  214 

2R2 


474 


INDEX. 


Phosphorus,   spontaneous    com- 
bustion of,  .         i 
binary  compounds  o 
inflames  in  bromine, 
in     nitrous 
oxide, 
peculiar    properties 
of,        .        .        . 
oxide  of, 
bottles,  how  made, 
iodide  of, 
sulphuret  of,  . 
Phosphoric  acid,  weight  of, 
character  of,     . 
Phosphuret  of  carbon, 
Phosphuretted  hydrogen,    . 
Pharmacopolite,           .         ... 
Picture,  sympathetic, 
Pinite,          
Pisolite,        .         .         . 

,.36 

;72 

84 
97 

119 
120 
121 
124 
132 
7f> 
121 
125 
124 
275 
13G 
262 
273 
345 
384 
425 
86 
155 
160 
193 
220 
249 
287 
422 
251 
291 
279 
123 
356 
382 
12 
29 
145 

107 
134 
144 
201 

ii 

144 

439 
29 
262 

66 
98 
407 
135 

291 

77 

Process,  metallurgic,  .  .       .       p.  215 
Protochloride  of  carbon,     .        .  108 
selenium,           .  133 
phosphorus,       .  123 
Protectors,  Davy's,      .         .         .45 
Protoxide  of  chlorine,         .        .     79 
hydrogen,       .         .     88 
nitrogen,        .        .     97 
iron,        .        .        .  157 
Prout  on  equivalent  volumes,     .     59 

Pyrites,         253 
Pyrophosphoric  acid,  .         .         .  122 
Pyrophysalite,     ....  267 
Pyrometer,  steam,       .        .        .135 
Pyromorphiie,      ....  275 
Putty,  tin,    144 

Quartz,  varieties  of,    .        .        .  259 

Rain,  causes  of,  .        .        .        .  457 
quantity  of,  in  different  re- 

Pitz  mountain,  fall  of, 
Pitchstone,  
Plagiostoma  dumosum, 
Platina,  fluorides  of,    . 
binary  compounds  of,    . 
properties  of, 
localities  of,  . 
reduction  of,          .  219, 
native,  .... 
Plesiomorphism, 
Plesiosaurus,        .... 
Plumbago,  
Polyedra  in  crystallography, 
Polyhalite,  
Polymerism,         .... 
Polypifers,  singular  power  of,     . 
Porphyritic  rocks, 
Potash  and  tartaric  acid  combine, 
precipitates  lime, 
Potassium,  ..... 
decomposes    carbonic 
acid, 
melting-point  of, 
binary  compounds  of, 
Potosi,  silver  mines  at, 
Powder,  of  various  colours,  sepa- 
rable after  mixture,  . 
ofcassius, 
Pressure,  variations  of, 
Precipitation,       .         .         .  x 
Prehnite  
Primary  compounds,three  classes 
of,     
Priestley  discovered  nitric  oxide, 
Primordial  rocks,        .    323.393. 
Prinsep's  experiments  on  fusion, 
Prisms  in  crystallography,  . 
Products  of  combustion, 

Ratios,  combining,  anomalous,    .     54 
Ravenna,  site  of,  changed,          .  340 
Reagents  for  analysis,         .         .  173 
Reduction  of  iron  ores,       .         .  221 
tin  ores,          .         .  225 
copper  ores,   .        .  228 
lead,       .        .        .228 
zinc,       .        .        .229 
Reefs,  coral,        ....  355 

Relics,  human,  pretended,          .  432 
Remains,  organic,  by  whom  stu- 
died,         .        .        .302 
fossil,  in  the  wealden 
group,       .        .        .423 
Resins,         166 
Respiration,  a  chemical  process,     13 
supported  by  oxygen,  74 
Revolutions  in  the  condition  of 
the  earth,         .        .                 .  303 
Rhodium,  binary  compounds  of,  156 
properties  of,       .         .  160 
Richter  on  combining  quantities,    68 
River,  Yellow,  of  China,    .        .340 
Roasting  of  iron  ore,  .        .        .  221 
Robinson  on  effects  of  rivers,     .  339 
Rock  crystal,       .         .                     259 
milk,  274 
Rocks,  disintegration  of,     .            335 
structure  and  composition 
of,          ....  380 

how  important  in  geology,  381 
non-fossiliferous,       .         .  382 
texture  of,         ...  385 
submedial,  formations  of,    393 
medial,     .        .        .        .412 

Proportions,  definite,  . 


52  Rodolphus  mine  at  Kremnitz,    .  200 


INDEX. 


475 


Rome  Delisle  on  crystals, 


p.  288 


equality  of  an 
gles  in  crys- 
tals, .  .  295 

Rossberg,  fall  of,        .        .        .  345 
Roubaudi's  remarks  on   marine 

exhalations,      ....  330 
Ruby  silver, 


256 


Silver,  fluoride  of, 


Saddle-shaped  strata, 
Safety  lamp,  Davy's,  . 
Sal-ammoniac,    .... 
Salt,  common,  primary  nucleus 

of,     . 

crystals  of,  .         .    284 
lakes,   .        .        . 
Salts,  combining  numbers  of, 

with  names  in  ate  and  tie,      77 
incompatible    in     mineral 

waters,    .  .         .  184 

soluble  and  insoluble,        .     68 

Sand  hills,  how  formed,     .        .  333 

floods,          .        .        .        .  333 

pillars  of,  moved  by  winds,  445 

Sandstone,  texture. of,         .        .  383 

-Snrc^coll, 164 

Saturated  air  deposits  moisture 

on  being  mixed,       .         .         .  447 
Saurian  animals  in  supermedial 
rocks 421 


melting-point  of,      . 

binary  compounds  of, 

chemical  properties  of,   . 

localities  of,    . 

absorbs     oxygen     when 
melted, 

native,     . 

sulphuret  of,    . 

ruby 

pits  of  the  North  sea, 
Simple  bodies,     .         .         .         . 
Simoom  wind,     .        .        .        . 
2SO  Sirocco  wind 


p.  86 
135 


155 
159 
193 


Skorodite, 

352jSlag  of  lead  ore,  how  used, 
68  Smelting  of  iron, 


Saussure  on  Neufchatel  lake,    .  343 

Saussure's  hygrometer,       .         .  448 

Schorls,       .        .        .        .        .266 

Sea,  mine  under  the,          .        .  206 

formative  effects  of  the,     .  353 

barriers  formed  by  the,       .  369 

breezes,  how  explained,     .  444 

Selenium,  general  account  of,    .     24 

binary  compounds  of,     73 

peculiar  properties  of,  132 

in  mineralogy,    .        .  257 

Selenious  and  selenic  acid,         .  133 

Separation,  line  of,  in  strata,       .  387 

Serpentine  mineral,    .        .        .  264 

rocks, 
Shale, 

Shafts,  sinking  of, 
Shap  granite, 
Shocks  of  earthquakes, 
Silica,  how  obtained  pure, 

and  silicates,    . 
Silex  in  mineral  waters,     . 
Sillimanite, 
Silicic  acid, 
Silicon,  general  nature  of, 

binary  compounds  of, 
peculiar  properties  of, 
chloride  of,     . 
Silico-fluoric  acid, 


.  218 
.  248 
.  255 
.  256 
.  321 
.  69 
.  445 
.  445 
.  275 
.  228 
.  222 


Snow-flakes  under  a  microscope,  283 


Snow,  theory  of, 

Soda,   sulphate   of,   in    mineral 


459 


181 
266 
144 
147 
.  148 
.  280 
.  170 
.  171 
172.  175 
.  173 
.  235 
.  11 
.  39 
215 
.  39 
.  346 
.  346 
.  169 
.  85 

Spawn  of  codfish,  minuteness  of,    32 
33 


water, 
Sodalite, 

Sodium,  binary  compounds  of, 
properties  of,  . 
melting-point  of,  . 
chloride  of,  .  . 
Soils,  nature  of,  .  .  . 
productiveness  of,  . 
analysis  of,  . 
moisture  in,  .. 
Solders,  table  of,  .. 
Solidity,  supposed  cause  of, 
Solution  effected  by  heat,  . 

of  metals,  how  tested, 
Solvent  power,  table  of,     . 
Solway  moss,  mud  deluge  at, 


p, 


Sonccbos  landsl 
Spallanzani,  on  carbonic  acid, 
Spar,  fluor 


Specific  heat  of  compounds, 

gravity  of  muriatic  acid,   92 
Spontaneous  combustion,  cause 
of, 


51 

382iStalactitic  limestone,  .        .        .  272 
.  383, Staple  Tor,  Great,       .        .        .327 

.  202J Starch 165 

.  375,  a  test  of  iodine,        .        .     82 

.  360|  States  of  bodies  depend  on  heat,    10 
.  117:Steam  pyrometer,        .         .         .  J35 
258. 261  j  engines  in  mines,     .        .204 

.  181  Steel,  nature  of,  •  224 

.2611  different  kinds  of,       .        .225 

.  117  Stilbite, 262 

21 1  Stones,  analysis  of,      .        .        .107 
72  Strata,  contorted,         .         .    386,  387 
116|  coal,  how  disposed,          .387 

119!  volcanic,          .         .         .395 

86 j Stratified  rocks,  .        .        .        .385 


476 


INDEX. 


Stratum,  invariable,   .               p.  308 
Stratus  cloud,      .        .                    455 
Stromboli,  eruptions  of,                  362 
Strontian,  compounds  of,                145 
properties  of,                   150 
Strontianite,        .        .                   271 
Strobilus,  fossil,  .        .                 .  402 

Temperature,  elevated,  promotes 
chemical  action,  p.  38 
increasing,   of  the 
lower  terrestrial 
strata,         .         .  309 
of  mines,        .        .  310 
mean,  of  different 
zones,          .        .  312 
of  lakes  and  seas,  .  315 
of  celestial  spaces,    316 
Temperaments  of  animals,         .  438 
Temples,  fire,      ....  328 

Subcarburet  of  hydrogen,           .  109 
Submedial  rocks,        .            397.  409 
Subchloride  of  carbon,                .  108 
Suber,          ...                 .166 
Substances  composing  the  earth's 
crust,        70 
Sugar,  chemical  properties  of,     .  164 
Sulphate  of  barytes,  how  decom- 
posed,   .        .        .65 
of   potash,    combining 
weight  of,         .        .     69 
Sulphates  in  mineral  waters,     .  181 
mineral,      .         .  277-279 
Sulphur,  general  account  of,      .     22 
electric  state  of,  .        .     43 
binary  compounds  of,  .     72 
burns  in  oxygen,          .     75 
and  iron  filings  decom- 
pose air,    .         .         .97 
decomposes  carburet  of 
hydrogen,          .         .110 
peculiar  properties  of,    126 
acids  of,         .         .         .127 
chloride  of,  .        .        .131 
bromide  of,  .        .        .  131 
and  sulphurets,    .         .  252 
Sulphuret  of  carbon,           .        .  131 
of  phosphorus,    .        .132 
Sulphurets,  composite,        .        .  255 
Sulphuretted  hydrogen,      .    129,  130 
Sump  in  a  mine,         .        .        .  204 
Superincumbent  rocks,       .        .  387 
Supermedial  rocks,    .        .        .  394 
fossils  in,       .  419 
Superior  rocks,    ....  396 
Syenite  rock,       ....  382 
Systems,  mineralogical,      .         .  237 
Swinestone,         ....  273 

Table  of  mineral  constituents,  .  243 
classes,    .        .  246 
of  vapours,                .        .     60 
of  gases,    .                         .     61 
Talcose  minerals,                .        .  263 
Tantalite,    .                                  .  268 
Tannin,       .                                  .  165 
Taper  extinguished  by  carbonic 
acid,         .                                  .  106 
Taste  of  minerals,       .        .        .241 
Telluri  um,  binary  com  pounds  of,  1  38 
properties  of,      .         .  141 
ores  of,               .        .  249 

Terra  pond  erosa,         .        .        .  149 
Tertiary  rocks,  fossils  in,    .         .  426 
Tesseral  system  of  minerals,      ."  297 
Testing  of  mineral  waters,         .  177 
Texture  of  rocks,        .        .        .  385 
Tides,  during  the  igneous  fusion 
of  the  earth,     ....  318 
Tilgate  forest,  fossils  of,      .         .  423 
Time,   measured    by  geological 
periods,    .....  370 
Tin,  oxide  of,      ....  258 
pyrites  254 
binary  compounds  of,  .        .  139- 
putty  144 
properties  of,         .         .         .  143 
localities  of,          .         .         .194 
ores,  how  reduced,       .         .  225 
grain  or  stream,   .        .        .  226 
Tincroft  mine,  section  of,  .        .  191 
Tinstone,  where  found,       .        .  187 
Tinning  of  copper  vessels,          .  232 
Titanium,     binary     compounds 
of.-.         .         .         .         .         .  137 
properties  of,      .         .  140 
oxides  of,    .        .        .  267 
Thorinum,  compounds  of,  .        .  145 
properties  of,     .        .153 
Thermal  springs,  deposits  from,    351 
Toad's-eye  woad  tin,  .        .        .  258 
Tomboro,  eruption  of,         .    333.  363 
Topaz  minerals,          .        .        .  267 
Tornados,    ....  335.  445 

Trachite,     384 
Trade  winds  443 
Transition  limestone,          .         .  383 
Transparency  of  minerals,          .  239 
Trap  rocks  384 
Traptuff,      384 
Travertin,  deposits  of,                 .  351 
Tremolite,  isomorphic,  with  an- 
thophyllite,      .        .        .        .287 
Trilobites  410 
Triplite        .                  .         .         •  276 

Trombus,     445 
Trough-shaped  strata,         .        .  388 
Truncation  of  crystals,        .        .  292 

INDEX. 


477 


Trunks  of  trees  found  in  quar- 
ries,      .         .        .  p.  4 
Tungsten,  compounds  of,   .        .1. 

properties  of,     .        . 
Tungstates,          .        .        .        .26 
Turner  on  atomic  weights, 
Turquois  of  Khorasan,        .        .27 
Tyfong,   phenomena    attending 
the 44 

Ulmin 16 

Unconfbrmable  rocks,        .        .  38 

Unit,  molecular,  of  Prout,  .        .     6 

Upheaving  of  mountains,  .        .  37 

Uranium,  binary  compounds  of,    13 

properties  of,       .        .  14 

oxide  of,  .        .  25*" 

Upas  valley,  in  Java,          .        .  32 

Uspalta  silver  vein,    .        .        .19 

Vanadium,  binary  compounds  of,  17f 
properties  of,     .        .  14 
and  vanadiates,         .  27( 
Valleys,  how  formed,          .        .34 
excavation  of,       .        .  37 
Vapour  of  bromine,     .        .        .8, 
Variable  winds  beyond  the  trades,  44' 
Vegetable  kingdom,    .        .         .  16<; 
analysis,     .        .        .  167 
matter  in  soils,          .  17( 
Vegeto-alkalies,          .        .        .167 
Vegetables,  constituents  of,        .  167 
fossil,  in  coal,  .        .  41 
intimate  components 

of,          ...     69 

living,  emit  oxygen,     74 

Veins,  intersection  of,         .        .191 

Vibrio,  minuteness  of  the,  .        .     3S 

Volatile  ingredients  in  minerals,  162 

Volcanic  eruption  at  St. Vincents,  331 

strata,   .        .        .        .397 

Volcanos,    quantity    of    matter 

ejected  by,     .        .  365 
submarine,         .         .  365 
causes  of,  .        .        .  367 
products  of,        .         .  385 
geological  relations  of,  357 
extent  and  number  of,  361 
intermitting,      .        .  382 
Voltaic  pile,  a  chemical  imple- 
ment,        41 

Volumes  combining,  .         .     57 

Vulcanists,  followers  of  Hutton,  301 


Wacke 384 

Washita  hot  springs,  .        .        .351 
Water  decomposed  by  galva- 
nism,    .        .        .       42.  99 
atomic  constitution  of,      .    53     anar  fire-spring, 


Water,  composition  of,   proved 

synthetically,        .        ».  88 
composition     of,     proved 

analytically,  .         .     89 

absorbs  carbonic  acid,  .  106 
mineral,  carbonated,  .  106 
general  account  of,  176 
evaporated  from  the  sea,  330 
geological  effects  of,  .  336 
of  rivers  extends  into  the 

ocean,  unmixed,    .        .  340 
motion  of,  over  the  British 

islands,          .  .  376 

spouts,  theory  of,  .  459 

absorbs  chlorine,  .     79 

weight  of,  in  a  cubic  inch 

of  air,    .        .  .  446 

Waves  degrade  the  land,  .  348 

Wax,    ....  .165 

Wealden  group  of  rocks,  .  395 

Vedging  out  of  mineral  veins,     187 
Weights,  atomic,  of  different  bo- 
dies, .        .        .        .53 
of  water  in  a  cubic  inch 

of  air,        .        .        .446 
Weiss    and    Mohs    on   mineral 

classification,  ....  297 
Veld  ing  of  iron,          .        .        .  156 
Veils,  on  the  causes  of  dew,     .  461 
Wenzell  on  chemical  affinities,      68 
(Verner's  system  of  mineralogy,  244 
theory  of  the  earth,       .  300 
division  of  rocks,  .391 

Vheal  ferry,  .  .  .  .208 
Vhirlwinds,  .  .  .  .445 
Vhite  mountains,  .  .  .  341 
Vinds,  causes  of,  ...  440 
proceed  to  windward,  .  441 
velocity  of,  how  estimated,  445 
/Vollaston's  theory  of  atmo- 
spheric limits,  32.  437 
scale  of  equivalents,  57 
theory  of  crystalliza- 
tion, .  .  .294 
goniometer,  .  .  296 
Vollastonite,  ....  261 
Vood,  chemical  nature  of,  .  166 
fossilized,  .  .  .401 
Vorks,  list  of,  on  chemistry,  .  185 
metallurgy,  .  235 
mineralogy,  .  282 
crystallography,297 
geology,  .  .  397 
oryctology,  .  435 
meteorology,  .  464 
necessary  for  mining  ope- 
rations, .  .  .  199 


.  329 


478  INDEX. 


Yttrium,  compounds  of,      .       p.  141 
properties  of,        .         .153 

Zangari,    countess,  spontaneous 

combustion  of,          ...     48 

Zinc  precipitates  iron,        .        .     28 

binary  compounds  of,         .  154 


Zinc,  properties  of, 
localities  of, 
oxides  of,     . 
silicate  of,   . 
Zirconium,  compounds  of, 
properties  of, 
Zirconite,    . 

; 

>.  157 
195 
257 
267 
45 
152 
261 

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mory serve  to  raise  a  host  of  reminiscences,  all  interesting  to  the  dili- 
gent and  inquiring  student. — With  my  wishes  for  the  success  of  the 
work,  accept  the  assurances  of  the  high  respect  with  which  I  sub* 
scribe  myself,  Your  obedient  servant, 

WALTER  R.  JOHNSON, 
Professor  of  Mechanics  and  Natural  Philosophy 
in  the  Franklin  Institute. 


[2] 

From  S.  JONES,  A.  M.  Principal  of  the  Classical  and  Mathematical 

Institute,  Philadelphia. 

I  have  attentively  examined  Pinnock's  improved  edition  of  Dr 
Goldsmith's  History  of  England,  published  by  Messrs.  Key  &  Biddle, 
of  this  city,  and  am  impressed  with  its  excellence.  I  have  no  hesita- 
tion in  expressing  my  full  approbation  of  the  work,  with  my  belief  that 
it  will  receive  a  liberal  patronage  from  an  enlightened  community. 

UthMo:  1834. 

I  consider  Pinnock's  edition  of  Goldsmith's  History  of  England  as 
the  best  edition  of  that  work  which  has  yet  been  published  for  the 
use  of  schools.  The  tables  of  contemporary  sovereigns  and  eminent 
persons,  at  the  end  of  each  chapter,  afford  the  means  of  many  useful 
remarks  and  comparisons  with  the  history  of  other  nations.  With 
these  views,  I  cheerfully  recommend  it  as  a  book  well  adapted  to 
school  purposes.  JOHN  M.  KEAGY. 

Friends'  Academy,  Philadelphia. 
We  fully  concur  in  the  opinion  as  expressed  above. 

SETH  SMITH,  WM.  A.  GARRIGUES, 

J.  H.  BLACK,  M.  SOULE, 

THOS.  COLLINS,  REV.  CHAS.  HENRY  ALDEN, 

JAMES  CROVVELL,  JOHN  EUSTACE, 

J.  B.  WALKER.  BENJ.  C.  TUCKER, 

S.  C.  WALKER,  HUGH  MORROW, 

T.  H.  WILSON.  WM.  McNAIN, 

J.  MADEIRA.  E.  H.  HUBBARD. 

WM.  MANN,  R.  LAKE, 

W.  MARRIOTT,  JOHN  WEBB, 

C.  B.  TREGO,  JOHN  ORD.  / 

URIAH  KITCHEN.  SAML.  CLENDENIN. 

THOS.  EUSTACE,  I).  R.  ASHTON. 

JOHN  IIASLAM.  J.  O'CONOR,  Scc'y  to  the  Phila. 

W.  CURRAN,  Association  of  Teachers. 

J.  STOCKUALE,  JOSEPH  WARREN, 

S.  II.  REEVES,  THOMAS  CONRAD, 

J.  HAYMAR,  THOS.  McADAM, 

W.  B.  ROSE,  REV.  SAML.  W.  CRAWFORD, 

CHAS.  MEAD,  A.  M.  Principal  of  Acadl.  Dept 

BENJ.  MAYO,  of  University  of  Pennsylvania. 

REV.  S.  M.  GAYLEY,  Wil-    M.  L.  HURLBUT, 

mington,  Del.  R.  W.  CUSHMAN, 

E.  FOUSE,  AUGUSTINE  LUDINGTON, 

J.  E.  SLACK,  JOHN  ERHARDT, 

JOSEPH  R.  EASTBURN,   OLIVER  A.  SHAW, 
A.  STEVENSON,  A.  D.  CLEVELAND. 

Baltimore,  Dec.  1&34. 
We  fully  concur  in  the  opinion  above  expressed. 

SAML.  JONES,  WILLIAM  HAMILTON. 

O.  W.  TREADWELL.  JOS.  WALKER, 

E.  BENNETT,  JAMES  SHANIJSY, 

E.  R.  HARNEY,  DAVID  RING, 

ROBT.  O'NEILL,  ROBT.  WALKER, 

N.  SPELMAN,  D.  W.  B.  McCLELAN, 

S.  W.  ROSZELL,  S.  A.  DAVIS, 

SAMUEL  HUBBELL,  JAS.  F.  GOULD, 

H.  O.  WATTS,  JOSH.  H.  CLARKE, 

C.  F.  BANSEMER,  FRANCIS  WATERS, 

D.  E.  REESE,  JOHN  MAGEE, 
S.  A.  CLARKE,  MIC1IL.  POWER. 
JOHN  FINLEY  A.  M. 


[3  ] 

New  York,  Dec.  183*. 
We  fully  concur  in  the  opinion  above  expressed. 

W.  R.  ADDINGTON,  THOMAS  GILDERSLIEVE, 

BERNARD  THORNTON,  MELANCTHON  HOYT, 

SIIEPPAKD  JOHNSTON.  THOMAS  V.  FOWLER, 

HORACE  COVELL,  J.  BAILE, 

P.  PERRINE,  SAMUEL  GARDNER, 

J.  B.  KIDDER,  G.   VALE, 

SOLOMON  JENNER.  J.  TAFT. 

JOSEPH  M'KEEN,  JOSIAII  J.  UNDERIIILL. 

EZRA  MUNDY.  C.  W.  NICHOLS, 

C.  CARTER,  THOMAS  M'KEE, 

LEONARD  HAZELTINF,  G.  J.  HORRER, 

JOSEPH  CHAMBERLAIN.  N.  DUNN, 

HENRY  SWORDS.  R.  TOB1TT, 

J.  M.  ELY,  SAMUEL  BROWN, 

W.  M.  SOMERVILLE,  ADN.  HEGEMAN, 

NORTON  THAYER,  WILLIAM  FORREST. 

Gentlemen — I  have  looked  (but  without  effect,  till  now)  for  a  reading- 
book  combining  at  once  interest,  chasteness  of  diction,  and  valuable  histo- 
rical information,  placed  in  so  enticing  a  form  as  to  induce  the  student  to 
read  it  for  itself  and  the  fac^s  it.  contains.  My  long  experience  has  taught 
me,  that,  without  interest,  the  pupil  will  not  trouble  himself  to  understand; 
and  without  understanding,  'tis  in  vain  to  teach,  either  for  improvement  in 
the  science  of  reading  or  for  information.  Happily,  teachers  have  in  Pin 
nock's  Goldsmith's  History  of  England  numerous  requisites  unknown  to 
the  best  of  its  predecessors.  Yours.  L.  BICKNELL. 

Philadelphia,  Nov.  1834. 

We  fully  concur  in  the  above.  WM.  ROBERTS. 

B.  N.  LEWIS. 

MESSRS.  KEY  &  BTODLB,  November  21,  1834. 

Gentlemen — 1  have  been  much  pleased  by  the  perusal  of  "Pinnock's  im- 
proved edition  of  Dr.  Goldsmith's  History  of  England."  I  think  it  fully  en- 
titled to  the  appellation,  improved,  and  should  rejoice  to  see  it  placed  in  the 
hands  of  all  our  American  youth.  That  you,  gentlemen,  may  meet  with 
that  encouragement  which  efforts  to  supply  the  wants  of  our  schools  merit, 
is  the  desire  of  Yours,  &c.  J.  H.  BROWN, 

Principal  of  the  English  and  Mathematical  Academy, 
No.  52  Cherry-street,  Philad. 

Review  of  "  Pinnock's  Goldsmith's  England,"  made  at  the  request,  and 
for  the  use  of  the  Lyceum  of  Teachers  of  the  city  of  Philadelphia , 
by  J.  H.  Brown,  Principal  of  Classical  Academy,  52  Cherry-street. 
PINNOCK'S  IMPROVED  EDITION  OF  DR.  GOLDSMITH'S  HISTOR1 
OF  ENGLAND,  illustrated  by  thirty  Engravings  on  wood.  The  first 
American,  corrected  and  revised  from  the  23d  English  edition,  pp.  453. 
Philad.  Key  &  Biddle,  1834. 

THERE  is  no  history,  except  our  own,  which  is  of  so  much  interest  to  us 
as  that  of  England ;  and  probably  no  history  of  England,  designed  for  the 
use  of  schools,  has  been  so  popular  as  that  of  Dr.  Goldsmith.  And  yet 
Teachers  have  long  felt  the  want  of  some  work  that  should  remedy  many 
defects  which  are  found  in  it.  Mr.  Pinnock  has  continued  the  history  to  the 
year  1832,  with  the  addition  of  "  questions  for  examination,"  at  the  end  of 
each  section ;  the  latter,  I  am  aware,  will  be  received  by  some  teachers  as 
of  doubtful  utility;  yet  the  judicious  teacher,  by  viewing  the  questions 
merely  as  hints  to  himself,  will  so  vary  them,  as  to  avoid  the  too  common 
error  of  neglecting  the  section  for  the  question.  A  more  important  addi- 
tion is  the  tables  of  contemporary  sovereigns  and  eminent  persons,  with 


[4  J 

copious  explanatory  notes,  and  remarks  on  the  politics,  manners,  and  litera 
ture  of  the  age.  So  far  as  the  original  work  of  Dr.  Goldsmith  is  preserved, 
I  shall  not  presume  to  speak.  The  notes  above  alluded  to  are  valuable 
additions  to  the  original  work;  and  happily  interspersed.  The  remarks 
on  politics,  manners,  and  literature,  though  judiciously  made,  fall  short  in 
amount  of  what  many  would  consider  proper  for  an  interesting  a'nd  instruc- 
tive history ;  yet,  as  this  part,  if  much  extended,  would  be  dull  and  spiritless 
to  the  young,  (for  whom  the  work  is  chiefly  intended,)  perhaps  the  author 
has  pursued  the  best  course. 

The  style  is  animated  and  clear,  abounding  sufficiently  in  anecdote  to 
make  it  interesting  to  the  young,  and  may  be  considered  the  most  interest- 
ing history  of  England  (for  the  use  of  schools)  extant. 

(Signed)  J.  H.  BROWN, 

Principal  of  Academy,  52  Cherry-st. 


GUY  ON  ASTRONOMY, 
AND  KEITH  ON  THE  GLOBES. 

THIRTEENTH  EDITION. 

GUY'S  ELEMENTS  OF  ASTRONOMY,  AND  AN 
ABRIDGEMENT  OF  KEITH'S  NEW  TREATISE 
ON  THE  GLOBE  S.  Thirteenth  American  edition,  with 
additions  and  improvements,  and  an  explanation  of  the 
Astronomical  part  of  the  American  Almanac.  Illustrated 
with  eighteen  plates,  drawn  and  engraved  on  steel,  in  the 
best  manner. 

RECOMMENDATIONS. 

A  volume  containing  Guy's  popular  treatise  of  Astronomy* and  Keith 
on  the  Globes,  having  been  submitted  to  us  for  examination,  and  care- 
fully examined,  we  can  without  any  hesitation  recommend  it  to  the 
notice  and  patronage  of  parents  and  teachers.  The  work  on  astronomy 
is  clear,  intelligible,  and  suited  to  the  comprehension  of  young  per- 
sons. It  comprises  a  great  amount  of  information,  and  is  well  illustrated 
with  steel  engravings  Keith  on  the  Globes  has  long  been  recognised 
as  a  standard  schoov-book.  The  present  edition,  comprised  in  the 
same  volume  with  the  Astronomy,  is  improved  by  the  omission  of 
much  extraneous  matter,  and  the  reduction  of  size  and  price.  On  the 
whole,  we  know  of  no  schooil-book  which  comprises  so  much  in  so 
little  space  as  the  new  edition  of  Guy  and  Keith, 

THOS.  EUSTACE,  W.  B.  ROSE. 

JOHN  IIASLAM,  CHAS.  MEAD, 

W.  CURRAN.  BENJ.  MAYO, 

SAML.  CLENDENIN,  HUGH  MORROW. 

S.  H.  REEVES,  J.  H.  BLACK, 

JOHN  STOCKDALE,  S.  C.  WALKER, 


[53 


J.  B.  WALKER. 
J.  E.  SLACK, 

JOSEPH  R.  EASTBURN, 

WM.  McNAIN, 
H.  O.  WATTS, 
J.  O'CONOR,  Secretary  to 

the  Phila.  Association  of 

Teachers. 
B.  N.  LEWIS. 
REV.  CHAS.  H.  ALDEN. 
BENJ.  C.  TUCKER, 
J.  H.  BROWN, 
JOHN  ORD, 
SETII  SMITH, 
WM.  ROBERTS, 
T.  H.  WILSON, 
JOSEPH  WARREN, 


TIIOS.  COLLINS, 

WM.  MANN, 

RIAL  LAKE, 

W.  MARRIOTT, 

C.  B.  TREGO, 

JOHN  ERHARDT, 

R.  W.  CUSHMAN. 

THO3.  McADAM, 

REV.  SAML.  W.  CRAWFORD 
Principal  of  Acadl.  Dept.  of  the 
University  of  Pennsylvania. 

O.  A.  SHAW, 

AUGUSTINE  LUDINGTON 

M.  SOULE, 

WM.  A.  GARRIGUES. 

M.  L.  HURLBUT. 


Baltimore,  Dec.  1834. 
We  fully  concur  in  the  opinion  above  expressed. 


E.  BENNETT, 

C.  F.  BANSEMAR, 
E.  R.  HARNEY, 
ROBT.  O'NEIIA, 
N.  SPELMAN, 

S.  W.  ROSZELL, 
SAMUEL  IIUBBELL, 

D.  E.  REESE, 
S.  A.  CLARKE, 
JOS.  WALKER, 

O.  W.  TREADWELL, 
REV.  S.  M.  GAYLEY,  Wil- 
mington, Del. 


JAMES  SHANLEY, 

DAVID  RING, 

ROBT.  WALKER, 

D.  W.  B.  McCLELAN, 

S.  A.  DAVIS, 

JAS.  F.  GOULD, 

JOS.  H.  CLARKE,  A.  M. 

FRANCIS  WATERS, 

JOHN  MAGEE, 

MICHL.  POWER, 

C.  D.  CLEVELAND. 


Willbraham,  Oct.  27,  1834. 

We  have  used  Guy's  Astronomy,  and  Keith  on  the  Globes,  as  a 
text-book,  during  the  past  year ;  it  is  in  all  respects  such  an  one  as  was 
wanted,  and  we  have  no  disposition  to  exchange  it  for  any  other  with 
which  we  are  acquainted. 

WM.  G.  MITCHELL, 

Lecturer  on  the  Natural  Sciences  and  Astronomy, 
in  Wesleyan  Academy,  Mass, 

New  York,  Dec.  1834. 
We  fully  concur  in  the  opinion  above  expressed. 

BERNARD  THORNTON,    W.  M.  SOMERVILLE, 


HORACE  COVELL, 
P.  PERRINE, 
J.  B.  KIDDER, 
SOLOMON  JENNER, 
JOSEPH  M'KEEN. 
C.  CARTER, 


NORTON  THAYER, 
THOMAS  GILDERSLIEVE, 
MELANCTHON  HOYT, 
THOMAS  V.  FOWLER- 
JOSEPH  BAILE, 
SAMUEL  GARDNER, 


LEONARD  HAZELTINE,    WILLIAM  FORREST, 
JOSEPH  CHAMBERLAIN,  C.  W.  NICHOLS, 
W.  R.  ADDINGTON,  THOMAS  M'KEE, 

HENRY  SWORDS,  ADN.  HEGEMAN. 

J.  M.  ELY,  G.  VALE. 

A3 


en 

BRIDGE'S  ALGEBRA. 

A  TREATISE  ON  THE  ELEMENTS  OF  ALGE 
BRA.  By  Rev.  B.  Bridge,  D.D.  F.R.S.,  Fellow  of  St, 
Peter's  College,  Cambridge,  and  late  Professor  of  Ma 
thematics  in  the  East  India  College,  Herts.  Revised  and 
corrected  from  the  eighth  London  edition. 

RECOMMENDATIONS. 

In  this  work  the  hitherto  abstract  and  difficult  science  of  Algebra  is 
.rimplified  and  illustrated  so  as  to  be  attainable  by  the  younger  class  of 
learners,  and  by  those  who  have  riot  the  aid  of  a  teacher.  It  is  al- 
ready introduced  into  the  University  of  Pennsylvania,  at  Philadel- 
phia; and  the  Western  University  at  Pittsburg.  It  is  also  the  text- 
book of  Gummere's  School  at  Burlington,  and  Friends'  College  at 
Hayerford,  and  of  a  great  number  of  the  best  schools  throughout  the 
United  States.  It  is  equally  adapted  to  common  schools  and  colleges. 

Philadelphia,  March  1th,  1833. 

Bridge's  Algebra  is  the  text-book  in  the  school  under  my  care;  and 
I  am  better  pleased  with  it  than  with  any  which  I  have  heretofore 
used.  The  author  is  very  clear  in  his  explanations,  and  systematic  in 
nis  arrangement,  and  has  succeeded  in  rendering  a  comparatively  ab- 
struse branch  of  science,  an  agreeable  and  interesting  exercise  both  to 
pupil  and  teacher.  JOHN  FROST. 

We  fully  concur  in  the  opinion  above  expressed. 

CHAS.  HENRY  ALDEN,        JOSEPH  WARREN, 
J.  O'CONOR,  Secretary  to       SAML.  CLENDENIN, 

the  Phila.  Association  of      S.  H.  REEVES. 

Teachers. 

GENTLEMEN — In 


you  my  opinion  respecting 

leave  to  say,  that  the  work  appears  to  be  well  adapted  to  the  instruct 
tion  of  students.  The  arrangement  of  the  several  parts  of  the  science 
is  judicious,  and  the  examples  are  numerous  and  well  selected. 

Yours,  respectfully,  ROBERT  ADRAIN. 

We  fully  concur  in  the  opinion  of  Bridge's  Algebra  as  expressed  by 
Dr.  Adrain. 

J.  HAYMER,  B.  N.  LEWIS, 

HUGH  MORROW.  JOHN  STOCKDALE, 

WM.  McNAIN,  W.  B.  ROSE. 

OLIVER  A.  SHAW.  BENJ.  MAYO, 

SETH  SMITH,  J.  H.  BLACK. 

SAML.  E.  JONES,  THOS.  McADAM, 

JNO.  M.  KEAGY,  REV.  SAML.  W.  CRAWFORD, 

THOMAS  CONRAD,  Principal  of  Acadl.  Dept.  of  the 

THOS.  COLLINS,  University  of  Pennsylvania. 

J.  E.  SLACK,  JOHN  ERHARDT, 

C.  B.  TREGO,  R.  W.  CUSHMAN, 

J.  B.  WALKER,  REV.  S.  M.  GAYLEY,  Wilming 

JOHN  HASLAM,  ton,  Del. 

W.  CURRAN, 


Baltimore,  Dec.  1834. 
We  fully  concur  in  the  opinion  above  expressed. 

E.  BENNETT.  O.  W.  TREADWELL 

E.  R.  IIAUNEY,  JOS.  WALKER, 

ROBT.  O'NEILL.  DAVID  RING, 

N.  SPELMAN,  ROBT.  WALKER, 

S.  W.  ROSZELL,  D.  W.  McCLELAN, 

SAMUEL  HUBBELL,  S.  A.  DAVIS, 

H.  O.  WATTS,  JOS.  H.  CLARKE,  A.M. 

C.  F.  BANSEMER,  FRANCIS  WATERS, 

D.  E.  REESE,  JOHN  MAGEE, 
S.  A.  CLARKE,  MICHL.  POWER. 

MESSRS.  KEY  &  BIDDLE,  November  22,  1834. 

Gentlemen — I  have  be'en  highly  gratified  by  an  examination  of 
"  Bridge's  Algebra,"  published  by  you;  and  think  it  well  entitled  to 
general  introduction  in  our  schools.  I  shall  give  it  a  preference  in  my 
academy  to  any  work  I  have  seen.  Respectfully,  yours, 

J.  tf.  BROWN, 
Principal  of  an  English  and  Mathematical  Academy, 

No.  52  Cherry-street,  Philadelphia. 
New  York,  Dec.  1834. 
We  fully  concur  in  the  opinion  above  expressed. 

P.  PEKRINE,  NORTON  THAYER,   . 

J.  B.  KIDDER,  THOMAS  GILDERSLIEVE, 

SOLOMON  JENNER.  MELANCTHON  HOYT, 

JOSEPH  M'KEEN.  THOMAS  V.  FOWLER, 

C.  CARTER,  JOSEPH  BAILE, 

LEONARD  HAZELTINE,    SAMUEL  GARDNER, 
W.  R.  ADDINGTON,  C.  W.  NICHOLS, 

HENRY  SWORDS,  THOMAS  M'KEE. 

W.  M.  SOMERVILLE, 


TO  TEACHERS  OF  FRENCH. 

L'ABEILLE-  POUR  LES  ENFANS,  ou  Lecons  Fran- 
Daises,  lere  Partie ;  a  1'usage  des  ecoles. 

Several  compilations  of  short  and  interesting  French  tales  have  been  lately- 
offered  to  the  public.  In  all  of  them,  however,  expressions  are  found, 
which,  although  familiar  to  the  ear  of  a  Frenchman,  offend  that  of  a  care- 
fully educated  American  child.  It  is  true  that  the  French  do  not  consider 
"Mon  Dieu !"  swearing;  with  them,  it,  is  equivalent  to  "Gracious!"  or 
"Oh,  dear!"  but  it  is  certainly  desirable  that  the  eye  and  the  ear  of  the 
pupils  of  schools  in  this  country  should  not  become  accustomed  to  such  ex- 
pressions. They  have  therefore  been  carefully  excluded  from  this  little 
work,  as  well  as  every  thing  of  an  unchristian  tendency.  It  is  designed  for 
the  first  reading  book.  The  style  is  simple,  the  sentences  short,  and  con- 
taining few  idioms,  inversions,  or  difficulties.  At  the  end  of  each  page  is  a 
translation  of  the  idiomatic  expressions  it  contains,  and  of  the  words  used 
in  an  acceptation  not  given  in  the  dictionary. 


IN   PRESS, 

The  following  new  and  valuable  works  for  Schools  and  Academws, 
PINNOCK'S   IMPROVED   EDITION  OF    DR.  GOLDSMITH'S 
HISTORY  OF  GRKECE,  revised   corrected   and  very  considerably 


[8] 

enlarged,  by  the  addition  of  several  new  chapters  and  numerous  use- 
ful notes,  with  questions  for  examination,  at  the  end  of  each  section 
Revised  from  the  twelfth  London  edition,  with  thirty  engravings,  by 
A  therton. 

PINNOCK'S  IMPROVED  EDITION  OF  DR.  GOLDSMITH'S 
HISTORY  OF  ROME,  to  which  is  prefixed  an  Introduction "*&  the 
study  of  Roman  history,  and  a  great  variety  of  information  throughout 
the  work,  on  the  Manners,  Institutions,  and  Antiquities  of  the  Romans, 
with  questions  for  examination,  at  the  end  of  each  section.  Revised 
from  the  twelfth  London  edition,  with  additions  and  improvements, 
with  thirty  engravings,  by  Atherton. 

HISTORY  OF  THE  UNITED  STATES.  K.  &  B.  have  in  prepa- 
ration such  a  History  of  the  United  States  as  has  been  long  and 
loudly  called  for  by  Teachers  and  Parents.  It  will  be  written  by  a 
gentleman  very  favourably  known  as  an  historian,  who  is  eminently 
capable  of  making  a  book  that  will,  in  every  respect,  satisfy  the  wants 
of  the  public.  The  style  of  getting  up  will  be  the  same  as  Pin- 
nock's  Goldsmith's  England,  which,  the  publishers  are  happy  to  say, 
has  met  wiih  the  decided  approbation  of  Teachers  and  Parents. 

SACRED  HISTORY  OF  THE  DELUGE,  illustrated  and  cor- 
roborated by  evidences  derived  from  tradition,  mythology,  and  ge- 
ology ;  adapted  to  courses  of  Scripti>re  Study,  in  colleges  and  higher 
seminaries,  and  to  general  use,  by  Francis  Fellowes,  A.  M.,  with  an 
Introductory  Essay  on  the  Study  of  the  Scriptures  as  a  part  of  liberal 
education.  By  the  Rev.  Chauncey  Colton,  A.  M.,  President  of  Bristol 
College. 

A  FAMILIAR  INTRODUCTION  TO  THE  PRINCIPLES  OF 
NATURAL  PHILOSOPHY,  adapted  to  the  use  of  schools.  Part  I 
comprising  Mechanics,  Hydraulics,  Hydrostatics,  Pneumatics,  Acous 
tics,  Pyronomics,  Optics,  Electricity,  Galvanism,  Magnetism.  With 
notes,  references,  questions  for  examination,  and  a  copious  index,  by 
Walter  R.  Johnson,  Professor  of  Mechanics  and  Natural  Philosophy  in 
the  Franklin  Institute  of  the  State  of  Pennsylvania. 

A  FAMILIAR  INTRODUCTION  TO  THE  PRINCIPLES  OF 
NATURAL  PHILOSOPHY,  adapted  to  the  use  of  schools.  Part  2, 
comprising  Chemistry,  Metallurgy,  Mineralogy,  Chrystallography,  Ge- 
ology, Oryctollogy,  and  Meteorology.  With  notes,  references,  ques- 
tions for  examination,  and  a  copious  index,  by  Walter  R.  Johnson, 
Professor  of  Mechanics  and  Natural  Philosophy  in  the  Franklin  In- 
stitute of  the  State  of  Pennsylvania. 

MANUAL  OF  CLASSICAL  LITERATURE,  from  the  German 
of  John  J.  Eschenburg.  With  additions,  by  Professor  Fiske  of  Am- 
herst  College.  The  work  comprises  four  parts: — 1.  The  Archaeology 
of  Greek  and  Roman  Literature  and  Art.  2.  The  Greek  and  Roman 
Classic  Authors.  3-  The  Greek  and  Roman  Mythology.  4.  The  Greek 
and  Roman  Antiquities. 

AN  ETYMOLOGICAL  DICTIONARY  OF  THE  ENGLISH 
LANGUAGE,  on  a  plan  entirely  new,  by  John  Oswald.  Revised  and 
improved,  and  especially  adapted  to  the  purpose  of  teaching  English 
Composition  in  schools  and  academies,  by  J.  M.  Keagy. 


THE  SCIENTIFIC  CLASS-BOOK 

THE  SCIENTIFIC  CLASS-BOOK  ;  OR,  A  FAMILIAR  IN- 
TRODUCTION TO  THE  PRINCIPLES  OF  PHYSICAL 
SCIENCE,  for  the  use  of  Schools  and  Academies,  on  the  basid 
of  Mr.  J.  M.  Moffat.  Part  I.  Comprising  Mechanics,  Hydrosta- 
tics, Hydraulics,  Pneumatics,  Acoustics,  Pyronomics,  Optics, 
Electricity,  Galvanism,  Magnetism.  With  Emendations,  Notes, 
Questions  for  Examination,  List  of  Works  for  Reference,  some 
additional  Illustrations,  and  an  Index.  By  Walter  R.  Johnson, 
A.M.,  Professor  of  Mechanics  and  Natural  Philosophy  in  the 
Franklin  Institute  of  the  State  of  Pennsylvania,  Member  of 
the  Academy  of  Natural  Sciences  of  Philadelphia,  one  of  the 
Vice-Presidents  of  the  American  Institute  of  Instruction. 

MESSRS.  KEY  &  BIDDLE,—  Philadelphia,  June  22,  1835. 

I  have  carefully  examined  your  "Scientific  Class-Book,  Part  I."  and  find 
it  what  has  for  some  time  been  much  wanted  in  our  academies  and  high 
schools.  The  emendations,  notes,  and  additional  illustrations,  are  important, 
and  what  might  be  expected  from  one  so  perfectly  at  home,  both  theore- 
tically and  practically,  in  the  range  of  Natural  Philosophy,  as  Mr.  Johnson 
is  extensively  known  to  be.  The  list  of  works  for  reference  will  be  appre- 
ciated by  intelligent  teachers.  I  have  introduced  it  as  a  Text- Book,  and 
commend  it  cordially  to  the  notice  and  examination  of  others. 

CHARLES  HENRY  ALDEN, 
Principal  of  the  Philadelphia  High  School  for  Young  Ladies. 

I  fully  concur  in  the  above.  SAMUEL  JONES. 

Philadelphia,  June1^,  1835. 

I  fully  concur  with  Messrs.  Frost,  Keagy,  and  Jones,  in  their  opinion  of 
Mr.  Johnson's  work  on  Natural  Philosophy,  and  shall  immediately  adopt  the 
book  as  the  best  I  know  of  for  use  in  my  own  and  other  schools,  in  this  city. 
in  which  I  give  instruction.  OLIVER  A.  SHAW. 

We  have  examined  Mr.  Johnson's  Scientific  Class-Book,  and  are  so  well 
satisfied  with  its  merits,  that  we  shall  adopt  it  as  a  class-book  on  Natural 
Philosophy  in  our  school.  S.  C.  &  J.  B.  WALKER. 

MESSRS.  KEY  &  BIDDLE, —  Philadelphia,  June  26,  1835. 

A  careful  examination  of  the  treatise  on  Mechanical  Philosophy,  entitled 
"The  Scientific  Class-Book,  Part  I."  has  satisfied  me,  that  it  is  by  far  the 
most  complete  class-book,  on  that  subject,  which  has  yet  fallen  under  my 
notice.  The  additions  made  by  Professor  Johnson,  particularly  the  bibli- 
ographical notes,  are  not  less  creditable  to  his  learning  and  sound  judgment, 
than  conducive  to  the  utility  of  the  work  for  the  purposes  of  instruction. 
The  volume  may  be  safely  recommended  as  a  standard  class-book  for 
schools  and  private  students.  JOHN  FROST. 

MESSRS.  KEY  &  BIDDLE, 

Gentlemen: — It  is  with  much  pleasure  that  I  have  examined  "The  Sci- 
entific Class-Book,"  on  the  basis  of  J.  M.  Moffat,  Esq.,  by  Walter  R.  John- 
son, A.M.  It  is  such  a  work  as  the  advancing  state  of  education  in  this 
eountry  particularly  demands  at  the  present  time.  I  hope  its  use  may 
fcecome  general. 

With  regard,  yours,  J.  H.  BROWN. 


[10] 


MESSRS.  KEY  &  BIDDLE, 

Gentlemen :— I  have  to  thank  you  for  a  copy  of  the  Scientific  Class-Book, 
prepared  by  Professor  Johnson,  from  the  work  of  MofFat.  1  have  been  so 
interested  in  the  perusal  of  it,  that  I  feel  almost  incapacitated  to  speak  criti- 
cally  of  its  character:  and  yet  this  interest,  perhaps,  may  speak  its  highest 
praiso.  The  exhibition  of  truth,  in  such  a  manner  as  to  allure  and  reward 
attention  with  delight,  even  where  the  charm  of  novelty  is  wanting,  is  cer- 
tainly a  rare  merit  in  an  elementary  treatise  on  the  Natural  Sciences.  The 
Scientific  Class-Book,  however,  is  very  far  from  being  made  up  of  stale 
categories.  It  embraces  a  surprising  amount  of  information  respecting  the 
most  recent  discoveries — information  which  will  not  be  found  in  any  other 
single  work  whatever.  I  would  cordially  recommend  it  as  a  book  admirably 
adapted,  by  its  fulness  and  simplicity,  by  its  happy  comuination  of  scientific 
accuracy,  with  a  charming  narrative  sort  of  ease,  at  once  to  awaken  the 
love  of  knowledge  and  to  impart  it  It  will  prove  a  most  valuable  work  to 
our  higher  schools  and  academies,  and  to  the  teachers  of  all  others. 

Yours,  truly,  R.  W.  CUSHMAN. 

MESSRS.  KEY  &  BIDDLE,  6th  Month  23d,  1835. 

Gentlemen: — I  have  examined  the  first  part  of  the  Scientific  Class-Book 
iust  published  by  you,  and  cheerfully  express  my  opinion,  that,  for  accuracy 
and  comprehensiveness,  this  work  contains  a  system  of  principles  and  illus- 
trations on  the  subject  on  which  it  treats,  superior  to  any  book  of  the  same 
size  and  price  intended  for  the  use  of  schools. 

As  this  volume  is  the  first  of  a  series  on  the  Mechanical  and  Physical 
Sciences,  the  public  may  confidently  expect  that  the  successive  parts,  when 
completed,  will  constitute  a  consistent  set  of  treatises  peculiarly  adapted  to 
the  present  wants  of  places  of  education.  JOHN  M.  KEAGY. 

We  cheerfully  concur  in  opinion  with  the  above  recommendations. 

JOS.  P.  ENGLE3,  WILLIAM  MARRIOTT, 

HUGH  MORROW,  RIAL  LAKE, 

WM.  A.  GARRIGUES.  BENJ.  MAYO, 

M.  SO1TLE.  JAMES  P.  ESPY, 

JACOB  PEIRCE,  REV.  SAML.  W.  CRAWFORD,  A.M., 

BENJ'N  C.  TUCKER,  Principal  of  the  Acadl.  Dept.  of  th« 

T.  G.  POTTS,  University  of  Pennsylvania, 

WM.  CURRAN,  THOS.  M.  ADAM, 

S.  BICKNELL,  CHARLES  MEAD, 

D.  R.  ASHTON,  JAS.  E.  SLACK, 
EL.  FOUSE,  L.  W.  BURNET, 
C.  FELTT,  WM.  MANN,  A.  M. 
THOS.  BALDWIN,  CHAS.  B.  TREGO. 
JOHN  STOCKDALE,                    WM.  ROBERTS, 
URIAH  KITCHEN,                        THOS.  COLLINS, 
THOS.  H.  WILSON,                       SAML.  CLENDENIN, 
SHEPHERD  A.  REEVES,             AUGUSTINE  LUDINGTON, 

E.  H.  HUBBARD,  JNO.  D.  GRISCOM, 
WILLIAM  McNAIR,  N.  DODGE, 
JAMES  CROWELL,                       JOHN  HASLAM. 
J.  O'CONNOR, 

New  York,  July,  1835. 

Having  examined  the  First  Part  of  the  Scientific  Class-Book,  we  feel  jus- 
tified in  concurring  in  the  above  favourable  recommendations. 
EDW.  D.  BARRY,  DAVID  SCHUPER, 

J.  M.  ELY,  F.  A.  STREETER, 

JOSEPH  McKEEN,  CHARLES  W.  NICHOLS, 

JONATHAN  B.  K I  ODER,  THOMAS  McKEE, 

PATRICK  S.  CASSADY,  G.  I.  HOPPER, 

WM.  R.  ADDINGTON,  J.  B.  PECK, 

RUFUS  LOCKWOOD,  S.  JENNER. 

NORTON  THAYER.  RICHARD  J.  SMITH. 

JOHN  OAKLEY, 


[11] 

From  Alexander  D.  Bache,  A.M.,  Professor  of  Natural  Philosophy  and 

Chemistry,  University  of  Pennsylvania. 
MESSRS.  KEY  &  BIDDLB, — 

Gentlemen : — I  have  examined,  with  much  pleasure,  the  first  part  of  the 
"Scientific  Class- Book."  The  additions  of  the  American  editor  appear  to 
me  to  have  well  adapted  the  book  for  use  in  schools  and  academies. 
Its  utility  to  the  general  reader  has  no  doubt  been  increased  by  the  same 
labours.  Very  respectfully,  yours, 

September  16,  1835.  A.  D.  BACHE. 

From  S.  Jones,  A.M.,  Principal  of  Mathematical  and  Classical  Institute. 

I  regard  "Guy's  Elements  of  Astronomy,"  and  "Keith  on  the  Globes," 
as  the  best  book  of  the  kind  which  1  have  examined,  and  feel  a  confidence 
that  the  price  of  the  work,  the  beautiful  and  appropriate  illustrations,  and 
the  handsome  and  correct  manner  in  which  the  treatises  have  been  exe- 
cuted by  the  publishers  and  editor,  as  well  as  their  intrinsic  merit,  will 
commend  them  to  every  parent  and  teacher. 

Philadelphia,  July  21,  1835.  S.  JONES. 

We  cordially  concur  in  the  recommendation  of  Messrs.  Key  &  Blddle's 
edition  of  Guy  and  Keith. 

REV.  DAVID  R.  AUSTIN,  A.M., 
Principal  of  Monson  Academy,  Monson,  Mass.,  September  21,  1835. 

T.  L.  WRIGHT, 

Principal  of  East  Hartford  Classical  and  English  School,  East  Hartford, 
September  23,  1S35. 

From  Simeon  Hart,jun.,  A.M.,  for  several  years  Principal  of  Farming- 
ton  Academy,  Connecticut. 
MESSRS.  KEY  &  BIDDLE, — 

I  have  examined,  with  considerable  attention,  "  Bridge's  Treatise  on  the 
Elements  of  Algebra,"  and  am  so  favourably  impressed  with  its  excellence, 
that  I  have  introduced  it  into  my  school  as  one  of  the  text-books  to  be  used 
by  students  in  algebra. 

I  have  also  examined,  with  much  pleasure,  "the  Scientific  Class-Book,  or 
a  familiar  Introduction  to  the  Principles  of  Physical  Science,"  and  would 
say,  in  the  words  of  the  closing  paragraph  of  the  preface,  "that  whatever 
merit  may  be  claimed  for  other  treatises  on  the  same  departments  in  science, 
this,  it  is  confidently  anticipated,  will  be  found  to  embrace  as  full  and  satis- 
factory a  view  of  the  subjects  on  which  it  treats,  as  any  similar  compilation 
which  has  hitherto  been  dedicated  to  the  service  of  American  youth." 

An  examination  of  "Guy's  Astronomy,"  and  "Keith  on  the  Globes,"  has 
resulted  in  the  conviction,  that  they  may  be  safely  recommended  to  parents 
and  teachers  as  works  well  calculated  to  interest  and  instruct  the  intelli- 
gent scholar. 

Pinnock's  improved  edition  of  Dr.  Goldsmith's  "Abridgment  of  the  His- 
tory of  Rome,"  and  his  improved  edition  of  the  "  History  of  England,"  are 
works  which  need  only  to  be  known  to  be  admired,  as  well  adapted  to  the 
wants  of  schools  and  academies  in  this  country. 

Respectfully  yours,  SIMEON  HART,  JtJN. 

Farmington,  Conn.,  September  4,  1835. 

From  Rev.  Dr.  Cornelius  D.  Westbrook,  Principal  of  a  Female  School, 
New  Brunswick,  New  Jersey. 

I  have  examined  Pinnock's  improved  edition  of  Dr.  Goldsmith's  "  History 
of  England,"  by  Key  &  Biddle  of  Philadelphia,  and  I  do  most  cheerfully 
recommend  it  to  teachers  of  schools  and  academies  as  the  best  arrano'» 
ment  of  that  very  popular  school  book  I  have  ever  seep 

New  Brunswick,  August  1,  1835 


[12]  ;•-, 

I  most  cordially  join  with  Dr.  Westbrook  in  his  opinion  of  Pinnock's 
Goldsmith's  England. 

REV.  DAVID  R.  AUSTIN,  A.M., 

Principal  of  Monson  Academy ',  Monson,  Mass.,  September  21, 1835. 

From  T.  L.  Wright,  A.M.,  Principal  of  East  Hartford  Classical  and 
English  School. 

I  very  cheerfully  concur  with  S.  Jones,  A.M.,  Principal  of  the  Classical 
and  Mathematical  Institute,  relative  to  "  Pinnock's  England  ;"  and  with  Dr. 
Adrain  in  his  opinion  expressed  of7  "  Bridge's  Algebra."  "  Pinnock's 
Rome,"  I  regard  as  well  adapted  to  the  use  of  schools  and  private  reading. 

East  Hartford,  September  23,  1835. 

from  Rev.  C.  D.  Westbrook,  D.D.,  Teacher,  New  Jersey. 

I  have  examined  Key  &  Biddle's  edition  of  "Guy's  Elements  of  Astro- 
nomy," and  "An  Abridgment  of  Keith's  Treatise  on  the  Globes."  Keith 
on  the  use  of  the  globes  is  too  well  known  to  need  any  recommendation  ; 
and  "  Guy's  Astronomy"  will  recommend  itself  to  any  one  who  wishes  to 
introduce  to  his  scholars,  or  to  his  children,  the  interesting  and  sublime 
study  of  astronomy.  CORNELIUS  D.  WESTBROOK. 

New  Brunswick,  August  1,  1835. 

FromN.  W.  Fiske,  A.M.,  V.D.M.,  Professor,  Amherst  College,  Mass. 
MESSRS.  KEY  &  BIDDLE, — 

Gentlemen  .•— With  great  satisfaction,  I  have  examined  your  editions  of 
"  Pinnock's  Goldsmith's  Rome"  and  "England."  They  are  executed  in  a 
very  convenient  and  attractive  form,  and  are  works  which  may  be  confi- 
dently recommended  for  use  in  all  our  schools  and  academies. 

The  "Scientific  Class- Book"  appears  to  me,  judging  from  the  portions  I 
have  yet  found  time  to  read,  a  very  excellent  work.  A  vast  amount  of  the 
most  interesting  and  valuable  knowledge  is  brought  into  a  small  compass, 
and  is  generally  presented  in  a  very  clear  and  happy  method.  I  hope  it 
will  obtain  extensive  circulation,  as  I  know  of  nothing  better  adapted  for 
common  instruction  in  the  sciences  which  are  treated  in  the  part  I  have 
seen.  Very  respectfully,  I  am  yours, 

September  21,  1835.  N.  W.  FISKE. 

In  the  opinion  expressed  by  Professor  Fiske,  respecting  the  "  Scientific 
Class-Book,  Part  I."  I  can  most  cheerfully  concur. 

E.  S.  SNELL,  A.M., 
Professor  of  Mathematics  and  Natural  Philosophy,  in  Amherst  College, 

Massachusetts. 

From  Rev.  David  R.  Austin,  A.M.,  Principal  of  Monson  Academy. 
I  fully  agree  with  Professors  Fiske  and  Snell,  in  regard  to  the  "  Scientifi« 
Class  Book,"  and  shall  adopt  it  in  the  institution  of  which  I  have  the  charge 

D.  R.  AUSTIN. 

I  concur  with  Professor  Fiske,  and  numerous  others,  in  relation  to  "  Pin 
nock's  Rome."  D.  R.  AUSTIN. 

Monson,  September  23,  1835. 

SamuelJones,  A.M.,  of  Philadelphia,  says  of  Bridge's  Algebra: — "Th 
lucid  style  of  investigating  subjects  pursued  by  Professor  Bridge  in  his 
'Conic  Sections,'  and  other  works,  is  found  commenced  here  :  the  arrange- 
ment is  methodical  and  good,  and  I  can  unhesitatingly  recommend  it  as  well 
worthy  of  the  places  of  the  ill-digested  compilations  used  in  many  schools." 
We  cordially  join  with  Mr.  Jones  in  his  opinion  of  Key  &  Biddle's  edition 
of  "Bridge's  Algebra."  H.  S.  AUSTIN. 

J.  M.  MOORE, 
J.  CROWLEY,  A.B. 


[13] 


I  can  unhesitatingly  subscribe  to  the  numerous  commendations  of 
"  Bridge's  Algebra."  DAVID  R.  AUSTIN, 

Principal  of  Monson  Academy,  Massachusetts, 

The  New  Jersey  Journal,  printed  August  25, 1835,  at  Elizabethtown,  N.  J., 

remarks  of  all  these  works : — 

"To  be  appreciated,  these  books  require  only  to  be  known.  We  most 
cordially  recommend  them  to  teachers  and  parents.  As  long  as  their  enter- 
prising  publishers  publish  such  books,  and  in  such  taste,  they  cannot  fail  to 
meet  with  encouragement." 

FromJ.  G.  De  Soter,  M.A.,  Professor  of  French,  Spanish,  and  Italian, 

Philadelphia. 

1  have  examined  "L'Abeille  pour  les  Enfans,"  published  by  Messrs.  Key 
and  Biddle  of  this  city,  and  am  so  much  pleased  with  the  pure  and  chaste 
style  of  the  selection,  that  I  shall  use  it  in  my  instruction  with  the  younger 
pupils.  J.  G.  DE  SOTER. 

Rev.  S.  North,  A.M.,  Professor  of  Languages,  Hamilton  College,  writes 
to  the  publishers  of  these  Histories  : — 

"After  an  attentive  examination  of  Goldsmith's  Histories  of  Rome  and 
England,  with  notes  and  other  additions  by  Pinnock,  it  gives  me  pleasure  to 
say,  that  I  think  them  the  best  editions  of  those  deservedly  popular  works 
which  have  yet  been  published."  He  adds  also — "  From  a  cursory  exami- 
nation of  'Bridge's  Algebra,'  'The  Scientific  Class-Book,'  and  'Guy's  As- 
tronomy,' they  appear  to  me  to  be  well  fitted  to  facilitate  the  progress  of 
students  in  the  respective  sciences  of  which  they  treat." 

Clinton,  Oneida  Co.,  N.  Y.,  September  28,  1835.  S.  NORTH. 

From  W.  H.  Scram,  Principal  of  a  Select  Classical  and  English  Academy, 

Troy,  New  York. 
MESSRS.  KEY  &  BIDDLE, — 

I  have  examined  the  edition  of  "Goldsmith's  England,"  prepared  by 
Pinnock  for  the  use  of  schools,  and  published  by  you.  Also,  your  editions 
of  "  Bridge's  Algebra,"  "  Guy's  Astronomy,"  "Keith  on  the  Globes,"  and 
the  "  Scientific  Class-Book,  Part  I."  and  consider  them  worthy  the  attention 
of  teachers  of  select  schools  and  academies.  I  shall  introduce  them  into 
my  school  as  soon  as  practicable. 

Yours  respectfully,  W.  H.  SCRAM,  A.M. 

Having  partially  examined  the  above  worK,  we  feel  no  hesitation  in  adding 
our  names  to  the  recommendations  already  obtained  from  gentlemen  in 
whose  honesty  and  capability  we  have  the  utmost  confidence. 

A.  CLARKE, 
JOS.  H.  CLARKE. 

We  fully  concur  in  the  above  recommendation. 
A.  B.  CLEVELAND,  S.  P.  SKINNER, 

A.  DINSMORE,  C.  H.  ROBERTSON, 
JAMES  WILKESON,                 "\  ROBERT  WALKER, 
WM.  HAMILTON,                      /  S.  CLARK, 

DAVID  RING,  JAMES  E.  SEARLEY, 

JAMES  SHANLEY,  {  E.  RHODES  HARNEY, 

E.  YEATES  REESE,  V  ROBT.  O'NEILL, 

N.  SPELMAN.  J  M.  POWER, 

B.  WALSH,  JNO.  PRENTISS, 
PARDON  DAVIS,  EDWARD  S.  EBBS, 
SAMUEL  HUBBELL,                                     MICHAEL  TONER. 
O.  W.  TREADWELL, 

Having  examined  Pinnock's  improved  edition  of  Dr.  Goldsmith's  History 
of  Rome,  I  unhesitatingly  say,  that  the  style  and  elegance  of  the  language, 


[14] 

the  arrangement  of  the  chapters,  and  the  questions  for  examination,  render 
it,  in  my  estimation,  a  most  valuable  school  book : — I  therefore  most  cheer- 
fully recommend  it  to  teachers,  and  do  confidently  trust  that  it  will  find  an 
extensive  introduction  into  the  schools  of  our  country. 
Baltimore,  September  23,  1835.  JA8.  F.  GOULD. 

We  fully  concur  in  the  above  recommendation. 
S.  P.  SKINNER,  A.  DINSMORE, 

C.  H.  ROBERTSON,  JAMES  WILKESON, 

ROBT.  WALKER,  jos.  H.  CLARKE, 

WM.  HAMILTON.  S.  A.  CLARKE, 

DAVID  RING,  JOSEPH  WALKER, 

JAMES  E.  SEARLEY,  JAMES  SHANLEY, 

SML.  ROZEL,  E.  RHODES  HARNEY, 

E.  YEAfES  REESE,  ROBT.  O'NEIL, 

N.  SPELMAN,  MICHAEL  POWER. 

B.  WALSH,  JNO.  PRENTISS, 

PARDON  DAVIS  EDWARD  S.  EBBS, 

SAMUEL  HUBBELL,  MICHAEL  TONER. 
O.  W   TREADWELL, 

From  Samuel  Jones,  A.M.,  Principal  of  the  Classical  and  Mathematical 

Institute,  Philadelphia. 

A  writer  of  so  honourable  a  popularity  as  Dr.  Goldsmith,  for  all  the 
graces  of  an  elegant,  polished,  and  pure  style,  and  whose  histories  have 
been  so  long  and  so  extensively  useful  to  youth,  certainly  needs  no  enco- 
mium. It  may  be  added,  however,  for  the  information  of  those  teachers 
who  are  not  acquainted  with  the  improvements  of  Pinnock,  that  he  has 
been  for  some  time  eminent  in  England  for  valuable  additions  to  school 
books.  Of  the  edition  of  Rome,  by  Messrs.  Key  &  Biddle  of  this  city,  it  ia 
believed  that  it  will  be  found  superior,  in  the  manner  of  "getting  up,"  to 
any  yet  published  in  this  country ;  while  its  attractive  appearance  and 
mechanical  execution  lead  me  not  only  to  hope,  but  confidently  expect,  that 
they  will  receive  a  liberal  return  for  their  investment. 


Philadelphia,  September  15,  1835. 
We  fully  concur  in  the  above. 

THOMAS  BALDWIN, 

D.  MAGENIS,  Teacher  of  Elocution. 

WM.  A.  GARRIGUES, 

CHARLES  HENRY  ALDEN, 

WILLIAM  MARRIOTT, 

THOMAS  CONARD, 

U.  KITCHEN, 

SETH  SMITH. 

J.  D.  GRISCOM, 

AUGUSTINE  LUDINGTON, 

CHAS.  B.  TREGO, 

THOMAS  EUSTACE, 

J.  H.  BROWN. 

JOHN  STEEL, 

T.  G.  POTTS, 

JOHN  P.  ENGLES, 

WILLIAM  MANN, 

L.  W.  BURNET, 

HUGH  MORROW, 

JOHN  EUSTACE, 


SAMUEL  JONES. 


SHEPHERD  A.  REEVES, 
JOHN  HASLAM, 
EL.  FOUSE, 
OLIVER  A.  SHAW, 
M.  L.  HURLBERT, 
RIAL  LAKE, 
BENJAMIN  MAYO, 
WILLIAM  M'NAIR, 
O.  K.  FROST, 
SAML.  CLENDENIN. 
THOS.  COLLINS, 
J.  O'CONNOR, 
JNO.  STOCKDALE, 

D.  R.  ASHTON. 
BENJAMIN  C.  TUCKER. 
JAMES  CROWELL, 
RICHARD  M'CUNNEY, 
JAMES  E.  SLACK, 
CHARLES  MEAD, 

E.  H.  HUBBARD, 


M.  A.  CRITTENDEN,  Principal  of  a        V.  VALUE, 

~Young  Ladies'  Seminary,  Phila.       EDWARD  POOLE. 
F  M.  LUBBREN, 


/ 


ADDITIONAL  B.ECOMIVIENDATIONS. 

From  Theodore  Strong,  LL.D.,  Professor  of  Mathematics  in  Rutgei*» 

College,  New  Jersey. 
MESSRS.  KEY  &  BIDDLB,— 

Gentlemen: — I  am  much  obliged  to  you  for  the  copies  of  the  "  Scientific 
Class-Book,  Part  I."  and  "  Bridges'  Algebra."  In  compliance  with  your 
request,  that  I  should  give  my  opinion  of  their  merits,  I  observed  that  from 
a  cursory  examination  I  have  been  led  to  forma  favourable  opinion  of  them. 
The  subjects  treated  of  (in  the  "  Class- Book")  appear  to  be  discussed  in  a 
very  clear  and  able  manner.  Besides,  there  are  several  important  subjects 
(such  as  pyronymics,  electro-magnetism,  &c.)  introduced,  which  are  not 
usually  treated  of  in  works  of  this  kind.  The  Algebra  is  written  in  a  very 
perspicuous  style,  and  the  subjects  investigated  appear  to  be  ably  handled 
Yours  respectfully,  THEODORE  STRONG. 

New  Brunswick,  July  27,  1835. 

From  C.  H.  Anthony,  Principal  of  Troy  Practical  School. 

I  have  examined  "L'Abeille  pour  les  Enfans,"  "  Bridge's  Algebra,"  and 
"Scientific  Class- Book,  Part  I.,"  the  books  lately  published  by  Messrs. 
Key  &  Biddle,  and  think  them  superior  to  most  other  works  on  the  subjects 
on  which  they  severally  treat.  So  high  an  opinion  have  I  of  their  utility, 
that  I  shall  endeavour  to  introduce  them  into  my  school  as  text-books. 

C.  H.  ANTHONY. 

Troy,  New  York,  July  30,  1835. 

From  A.  B.  Myers,  B.A.,  Principal  of  Whitehall  Academy. 
MESSRS.  KEY  &  BIDDLB, — 

Gentlemen: — I  have  been  much  pleased  by  an  examination  of  "Pinnock's 
History  of  England,"  " Guy's  Astronomy."  "Keith  on  the  Globes."  and 
the  "Scientific  Class-Book,"  together  with  "Bridge's  Algebra."  I  think 
them  all  well  entitled  to  a  general  introduction  into  our  schools.  I  cheer- 
fully give  them  the  preference  to  any  other  books  of  the  kind  that  Lave 
fallen  into  my  hand 

Yours,  &c.  'A.  B.  MYERS. 

Whitehall  New  York,  1835. 

From  G.  W.  Francis,  A.M.,  Principal  of  a  Select  School,  Troy,  N.  Y. 
MESSRS.  KEY  &  BIDDLE, — 

Gentlemen: — I  have  formed  so  favourable  an  opinion  of  "Bridge's  Alge- 
bra," "Johnson's  Scientific  Class-Book,"  and  "Pinnock's  Goldsmith's 
Rome,"  published  by  you,  that  I  purpose  to  introduce  them  into  my  school 
as  soon  as  practicable. 

Yours,  G.  W   FRANCIS. 

Troy.  July  29.  1835. 

Geneva  College,  N.  If.,  1st  Dec.  1835. 
MESSRS.  KEY  &  BIDDLE, — 

Gentlemen : — A  few  weeks  since  your  agent  desired  my  opinion  as  to  the 
merits  of  "Pinnock's  Goldsmith's  England,"  "Pinnock's  Goldsmith's  Rome," 
"Guy's  Astronomy,"  and  the  "Scientific  Class-book,  Part  First."  I  have 
cursorily  examined  each,  as  requested,  and  have  formed  the  following 
opinion,  viz.  : — 

v  Pinnock's  Goldsmith's  England  and  Pinnock's  Goldsmith's  Rome  ar« 
works  of  great  merit ;  are  well  adapted  to  ensure  the  objects  intended,  and 
ought  to  be  extensively  used  in  all  the  schools  in  the  country. 

Guy's  Astronomy  contains  all  that  is  necessary  on  that  subject  for  ele- 
mentary instruction ;  more  is  not  desirable  in  the  absence  of  demonstrative 
reasoning,  which  cannot  be  advantageously  employed  without  previous 
thorough  mathematical  preparation. 

The  Scientific  Class-book,  Part  First,  is  the  best  work  of  the  kind  with 
which  I  am  acquainted.  If  the  learned  author  executes  the  second  part  with 
the  same  judgment  and  ability  as  he  has  the  first  part,  this  treatise  will 
deserve,  and  no  doubt  receive  very  extensive  patronage. 

Very  respectfully  yours,  &c., 

HORACE  WEBSTER. 


[16] 

.stfromJohn  M.  Keagy,  M.D., Principal  of  Friends'  Academy, Philadelphia. 
j^       Pinnock's  edition  of  "Goldsmith's  Rome"  has  several  very  useful  addi- 
jr  tions;  the  one  an  introduction,  containing  an  abridged  view  of  Roman 

r-  Geography  and  Antiquities,  and  the  other  a  very  appropriate  extension  of 

Roman  history  to  the  subjugation  of  the  Empire  by  the  Northern  Barbarians. 
This  improved  edition  of  "Goldsmith's  Rome"  will,  no  doubt,  retain  its 
place  in  our  schools  as  one  of  the  best  abridgments  of  the  history  of  that 
interesting  people. 

JNO.  M.  KEAGY. 

From  J.  M'Intyre,  English  and  Classical  Teacher,  Philadelphia. 

Pinnock's  edition  of  "  Goldsmith's  Rome"  is,  in  my  opinion,  superior  to 
any  other :  the  introductory  chapters  contain  much  information  new  and 
interesting,  and  present  a  favourable  specimen  of  the  editor's  historical 
powers.  To  speak  of  Goldsmith's  style  is  unnecessary  :  but  of  the  style 
of  the  present  editor,  we  may  state,  that  it  is  eminently  chaste,  and  little 
deficient  either  in  purity  or  precision ;  it  is  dignified,  yet  not  stiff;  concise 
and  strong,  without  roughness  or  obscurity. 

Pine  Street,  October  9,  1835. 

MESSRS.  KEY  &  BIDDLE,— 

Gentlemen: — I  have  perused,  with  much  interest,  the  "Scientific  Class- 
Book,"  edited  by  Professor  Johnson.  Allow  me  to  unite  my  acknowledg- 
ments, with  those  of  other  teachers,  for  so  valuable  an  aid  to  the  business 
of  instruction.  The  whole  work  forms  the  most  clear,  exact,  and  compre- 
hensive elementary  treatise  that  I  have  seen  on  the  subjects  which  it 
embraces.  The  value  of  the  work  is  still  farther  enhanced  as  the  produc- 
tion of  one  long  familiar  with  the  topics  on  which  it  treats,  and  thoroughly 
versed  in  the  mode  of  presenting  them  to  the  mind,  in  the  Various  forms 
of  practical  instruction. 

Yours,  &c.  WILLIAM  RUSSELL. 

Philadelphia,  October  6,  1835. 

From  Mr.  Myers,  A.B.,  of  Vermont. 

Gentlemen: — I  think  your  school-books  should  be  introduced  into  all  our 
schools  as  soon  as  possible.  They  are  just  the  books  which  have  long  been 
needed,  and  the  sooner  they  are  brought  into  use  the  better. 

Yours,  &c.  ALLEN  B.  MYERS. 

From  a  communication  to  the  Norwich  Courier  of  October  14th,  1835,  by  the 
Rev.  John  Storrs,  Principal  of  the  Norwich  Female  Academy,  the  fol- 
lowing extracts  are  taken : — 

First — The  first  excellence  of  this  work  ("  The  Scientific  Class-Book")  is 
the  simplicity  of  style  in  which  it  is  composed.  Secondly — The  familiarity 
of  its  illustrations  is  another  excellency.  Thirdly — Connected  with  this  is 
an  abundance  and  variety  of  illustration  ;  so  that  the  subjects  presented  are 
brought  to  the  understanding  of  the  most  obtuse  intellects.  Fourthly — 
Another  excellency  of  the  work  is  a  due  regard  to  brevity  ;  which  cannot 
be  said  of  all  books  treating  of  the  sciences.  Fifthly — In  this  book  is 
gathered  a  large  amount  of  practical  knowledge.  Hence  men  in  practical 
life  will  find  in  it  much  valuable  information,  and  many  sensible  hints.  On 
account  of  these  excellencies  I  can  most  cheerfully  recommend  the  work 
to, your  readers. 
Norwich,  Conn.,  October  13,  1835.  JOHN  STORRS. 

MESSRS.  KEY  &  BIDDLE, — 

Gentlemen: — "Goldsmith's  History  of  England,"  as  corrected  and  ar- 
ranged in  your  recent  edition,  is,  in  my  opinion,  the  best  book  on  its  subject 
which  can  be  put  into  the  hands  of  young  persons.  The  style  of  the  origi- 
nal work  lias  an  attractive  charm  in  the  ease  and  fluency  of  the  narrative. 


[17] 

It  ia  a  pleasing  model  of  composition,  and  furnishes  excellent  matter  for  the 
exercises  of  reading.  As  a  book  of  history,  however,  it  needed  revision 
and  emendation.  These  it  has  undergone)  to  the  best  advantage,  in  its 
present  form ;  the  American  editor  having  used  every  exertion  to  render 
it  an  acceptable  and  useful  class-book. 

I  am,  gentlemen  yours,  with  much  respect, 
Philadelphia,  7th  October,  1835.  WILLIAM  RUSSELL. 

MESSRS.  KEY  &  BIDDLE, — 

Gentlemen : — I  have  availed  myself,  with  much  satisfaction,  of  the  useful 
volume  comprising  "Guy's  Astronomy"  and  "Keith's  Treatise  on  the 
Globes."  The  former,  in  its  original  shape,  was  one  of  the  best  elementary 
books  of  its  kind ;  and  the  great  extent  of  the  latter  was  the  only  obstacle 
to  its  universal  use.  The  sole  form  in  which  it  could  be  used  with  young 
learners,  was  by  the  transcription  of  the  most  important  parts  of  it.  To 
one  accustomed  to  use  it  in  this  way,  for  successive  years,  your  excellent 
selection  was  a  most  valuable  and  welcome  substitute. 

The  volume  embracing  these  two  indispensable  works  forms  one  of  the 
most  compact  and  economical  school-books  which  the  American  press  has 
furnished.  I  am,  gentlemen,  yours  i-espectfully, 

Philadelphia,  7th  October,  1835.  WILLIAM  RUSSELL. 

"Guy's  Elements  of  Astronomy"  has  now  been  before  the  public  nearly 
twenty  years.  During  that  period,  the  improvements  in  this  popular  trea- 
tise have  kept  pace  with  the  great  improvements  in  the  science  itself,  and 
in  the  modes  of  teaching  it.  It  is  now,  I  believe,  recognised  throughout  the 
United  States,  and  in  England,  as  one  among  the  best  class-books  in  this 
"  y  which  we  have  in  our  language.  It  is  some 
he  most  popular  treatises  on  the  same  subject, 

r Jand, 

transcripts  from  Guy. 

"  Keith  on  the  Globes,"  as  now  adapted  to  our  schools,  is  perhaps  unequal- 
led by  any  similar  work ;  and  the  union  of  these  two  in  one  volume  of  mode- 
rate size,  was  a  fortunate  arrangement,  and  has  supplied  a  great  desidera- 
tum to  the  cause  of  education,  for  which  the  publishers  are  entitled  to  much 
commendation.  E.  H.  BURRITT. 

New  Britain,  Conn.,  Dec.  7,  1835. 

Professor  Johnson  has  rendered  the  public  an  invaluable  service  in 
"Scientific  Class-book."  It  is  a  treasure  of  useful  knowledge,  happily  adaptt 
not  only  to  the  wants  of  the  student,  but  not  less  so  to  the  general  rea< 
There  is  so  much  intrinsic  merit  in  this  volume,  so  much  of  what  e\ 
youth  of  every  grade  in  the  country  should,  in  some  sense,  be  familiar  i 
that  I  am  sure  it  needs  only  to  be  known  to  ensure  it  a  wide  circulat 
Aside  from  its  peculiar  merit  as  a  class-book  for  the  higher  schools,  I  \ 
say  to  every  young  man  in  the  United  States,  about  to  engage  in  the  bus 
of  life.  Let  the  Scientific  Cl-ass-book  be  your  constant  companion. 

New  Britain,  Conn.,  Dec.  7,  1835.  E.  H.  BUI 

I  have  long  been  acquainted  with  Mr.  Bridge's  larger  system  of 
and  am  gratified  that  an  author  so  competent  to  the  task  has  furry 
elementary  treatise  for  junior  pupils.    This  rs  so  simple,  clear, 
arranged,  as  to  place  the  acquisition  of  this  very  essential  branch 
matics  within  the  reach  even  of  common  schools.  The  importan' 
a  work,  of  great  perspicuity  in  the  rules  and  examples ;  of  explaU 
and  familiarly  the  dependence  and  connexion  between  each  sue/ 
and  thus  conducting  the  learner,  by  easy  gradations,  from  the 
pies  of  a  simple  equation  to  the  investigation  of  the  higher  am 
to  have  been  fully  understood  and  dnly  appreciated  by  the, 
valuable  elementa'ry  treatise  on  Algebra.  E;  H^BU^ 

New  Britain,  Conn.,  Dec.  7,  1835. 


branch  of  Natural  Philosophy  which  we  have  in  our  language.  It  is  some 
evidence  of  this,  that  one  of  the  most  popular  treatises  on  the  same  subject, 
since  published  in  England,  and  two  others  in  this  country,  are  chiefly  but 


[18] 


From  Rev.  W.  C.  Fowler,  A.M.,  C.  A.  S.f  Professor  Middkbury  College, 
Vermont. 

The  "Scientific  Class-book"  is  admirably  adapted  to  the  use  of  high 
schools  and  academies,  as  an  introduction  to  the  principles  of  physical 
science.  It  is  neither  a  meagre  sketch  on  the  one  hand,  nor  on  the  other 
is  it  overloaded  with  facts.  The  principles  are  distinctly  announced,  and 
the  illustrations  and  proofs  are  interesting  and  satisfactory. 

"Goldsmith's  Rome"  and  "Goldsmith's  England,"  coming  from  one  who 
"adorned  every  thing  that  he  touched,"  needed  only  what  has  been  done 
by  Pinnock  to  make  them  as  well  suited  to  the  purposes  of  class-books  in 
academies,  as  they  were  before  to  general  reading. 

"Guy's  Astronomy"  and  "Keith  on  the  Globes,"  two  in  one,  are  excel- 
lent for  unfolding  a  science  in  which,  from  the  grandeur  of  the  objects  pre- 
sented, every  youth  and  every  man  must  feel  a  strong  curiosity  and  a  deep 
interest.  WILLIAM  C.  FOWLER, 

Professor  of  Chemistry. 

From  Rev.  David  R.  Austin,  A.M.  Principal  of  Monson  Academy, 

Monson,  Mass. 

"  Bridge's  Algebra"  has  been  adopted  as  a  text-book  in  Monson  Academy, 
and  I  can  state,  with  the  utmost  confidence,  that  it  is  superior  to  any  work 
of  the  kind  within  my  knowledge.  The  arrangement  is  methodical,  the 
statement  of  principles  clear  and  concise.  The  pupils  are  uniformly  pleased 
with  it,  and  their  progress  greatly  facilitated.  D.  R.  AUSTIN. 

Jan.  19,  1836. 

The  "Scientific  Class-book"  has  been  introduced  into  Monson  Academy, 
and  I  do  not  hesitate  to  say  that  this  book  far  exceeds  any  elementary  trea- 
tise upon  similar  subjects  which  1  have  seen.  This  work  deserves  the 
patronage  of  the  public  ;  and  1  can  cordially  recommend  it  as  a  suitable  book 
to  introduce  into  common  schools  and  academies  throughout  the  land. 
Jan.  19,  1836.  D.  R.  AUSTIN. 

From  the.  Misses  Barnard. 

We  have  looked  through  your  little  volume  of  "  Sacred  History,"  and  are 
very  much  pleased  with  it.  We  have  long  felt  the  deficiency  of  our  pupils 
in  this  branch  of  education,  and  are  happy  to  introduce  to  their  notice  a 
work  so  well  worthy  their  attention  as  is  yours,  in  the  humble  opinion  of 

MISSES   BARNARD. 

Philadelphia,  Aug.  1st,  1835. 
MESSRS.  KEY  <fc  BIDDLE, 

Gentlemen  —  I  have  examined  Pinnock's  improved  edition  of  Dr.  Gold- 
smith's abridgement  of  the  "History  of  Rome,"  and  consider  it  eminently 
adapted  to  the  use  of  schools,  academies,  and  private  students.     The  intro- 
ductory chapters  elucidate  clearly  and   forcibly  the  manners,  customs, 
laws,  religious  and  civil  institutions  of  the  Romans  ;  and  form  a  valuable 
prelude  to  the  history  of  a  state  which,  from  obscure  and  feeble  origin,  ex- 
tended its  arts  and  arms  over  every  known  habitable  spot  of  earth. 
With  my  best,  wishes  for  the  success  of  your  many  useful  publications, 
I  am,  respectfully,  yours, 

WM.  ROBERTS, 

Teacher  of  Young  Ladies'  Seminary, 

i  No.  133  Lombard  Street. 

w 
n, 


G  S.  WHITFORD. 


VB  35746 


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